DEPR: remove assert_panel_equal
There's a kludge for test_pickle and test_packers to ignore the "panel" keys in the legacy files.  Longer-term we'll need to re-generate the legacy files without the Panels in them.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25238?src=pr&el=h1) Report
> Merging [#25238](https://codecov.io/gh/pandas-dev/pandas/pull/25238?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/04df22fbeec782f474bcff20480eded04e0d1d82?src=pr&el=desc) will **decrease** coverage by `0.19%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25238/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25238?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##           master   #25238     +/-   ##
=========================================
- Coverage   91.89%    91.7%   -0.2%     
=========================================
  Files         166      166             
  Lines       52226    52203     -23     
=========================================
- Hits        47993    47871    -122     
- Misses       4233     4332     +99
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.24% <ø> (-0.2%)` | :arrow_down: |
| #single | `41.96% <ø> (-0.17%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25238?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25238/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `87.57% <ø> (-0.18%)` | :arrow_down: |
| [pandas/core/panel.py](https://codecov.io/gh/pandas-dev/pandas/pull/25238/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcGFuZWwucHk=) | `71.74% <0%> (-8.53%)` | :arrow_down: |
| [pandas/core/ops.py](https://codecov.io/gh/pandas-dev/pandas/pull/25238/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvb3BzLnB5) | `91.76% <0%> (-2%)` | :arrow_down: |
| [pandas/core/indexing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25238/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhpbmcucHk=) | `92.27% <0%> (-1.61%)` | :arrow_down: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/25238/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `94.16% <0%> (-0.53%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25238?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/25238?src=pr&el=footer). Last update [04df22f...f8506e2](https://codecov.io/gh/pandas-dev/pandas/pull/25238?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/25238?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@7ee5b92`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25238/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25238?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #25238   +/-   ##
=========================================
  Coverage          ?    91.7%           
=========================================
  Files             ?      166           
  Lines             ?    52190           
  Branches          ?        0           
=========================================
  Hits              ?    47863           
  Misses            ?     4327           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.25% <ø> (?)` | |
| #single | `41.95% <ø> (?)` | |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25238?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25238/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `87.57% <ø> (ø)` | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25238?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/25238?src=pr&el=footer). Last update [7ee5b92...36b0bb6](https://codecov.io/gh/pandas-dev/pandas/pull/25238?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 looks fine. ping on green.

your kludge in pickle / msgpacks tests is ok. yeah should prob just rewrite those files, can you create an issue about this. (could even have a script which autogenerates for each version, basically create a new conda env and then write the file). ping thanks!