COMPAT: 32-bit compat for tz-conversions
xref #18777

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18778?src=pr&el=h1) Report
> Merging [#18778](https://codecov.io/gh/pandas-dev/pandas/pull/18778?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/265e3272b8709a7be274321ee8b505a0e74b8e10?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18778/graphs/tree.svg?token=eZ4WkYLtcO&height=150&src=pr&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/18778?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18778      +/-   ##
==========================================
- Coverage   91.61%    91.6%   -0.02%     
==========================================
  Files         153      153              
  Lines       51367    51367              
==========================================
- Hits        47061    47054       -7     
- Misses       4306     4313       +7
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.46% <ø> (ø)` | :arrow_up: |
| #single | `40.76% <ø> (-0.12%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18778?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18778/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18778/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18778/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `82.52% <0%> (+0.19%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18778?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/18778?src=pr&el=footer). Last update [265e327...94ca87f](https://codecov.io/gh/pandas-dev/pandas/pull/18778?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
