TST- Fixing issue with test_parquet test unexpectedly passing
- [x] closes #24479 
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

This pr aims to make the failing test_parquet not strict since it now passes at least on my machine of Mac 10.14 running the latest python 3.7 and conda.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=h1) Report
> Merging [#24480](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/80295f9483176b1335226680f1b55f09ded9ad46?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24480/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24480   +/-   ##
=======================================
  Coverage   92.32%   92.32%           
=======================================
  Files         166      166           
  Lines       52298    52298           
=======================================
  Hits        48285    48285           
  Misses       4013     4013
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.74% <ø> (ø)` | :arrow_up: |
| #single | `43.06% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=footer). Last update [80295f9...d9bc62d](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=h1) Report
> Merging [#24480](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/8dd9cdd9652c9cb499e02d552ed991081c920e6f?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24480/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #24480      +/-   ##
==========================================
- Coverage   92.32%   92.31%   -0.01%     
==========================================
  Files         166      166              
  Lines       52328    52335       +7     
==========================================
+ Hits        48310    48312       +2     
- Misses       4018     4023       +5
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.73% <ø> (-0.01%)` | :arrow_down: |
| #single | `43.04% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/arrays/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/24480/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2RhdGV0aW1lcy5weQ==) | `97.77% <0%> (-0.67%)` | :arrow_down: |
| [pandas/compat/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/24480/diff?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9fX2luaXRfXy5weQ==) | `57.91% <0%> (-0.39%)` | :arrow_down: |
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/24480/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `93.73% <0%> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=footer). Last update [8dd9cdd...41427a3](https://codecov.io/gh/pandas-dev/pandas/pull/24480?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @datapythonista do we have the xfails shows somewhere? e.g. https://dev.azure.com/pandas-dev/pandas/_build/results?buildId=6035 I don't exactly understand the rationale behind the builds, but a modern Mac build sounds reasonable.

Without know much about the builds we have, what would make sense to me is to have a "base" dependencies file, and have a build with the same conda deps in Linux, Windows and Mac. Happy to work on this if it makes sense.

Regarding xfails, I wanted to standardize the output of all the builds in #23115 (which still needs a bit of work). Not sure what is the preferred output, I think we have `-r sxX` in some places (like the windows builds). Seems to be passing now. So to catch up a bit, we still need the xfail because of `pyarrow` and `fastparquet` having differing versions on windows? Or is it Mac now supports cross-compat with differing reading/writing engines, but Windows doesn't? no i think this is ok now @jreback I have an unpublished branch that removes the xfail completely from both windows and mac. It seems to be passing the CI tests. Can you advise if we should take out the xfail completely? yeah might be good to try that Looks like removing the xfail works, seems whatever issue arose from running this test (old dependency maybe?) is gone now. Thanks @RjLi13!