BUG: setitem with boolean mask and tz-aware DTI
closes #16889 

 - [x] closes #xxxx
 - [x] tests added / passed
 - [x] passes ``git diff upstream/master --name-only -- '*.py' | flake8 --diff`` (On Windows, ``git diff upstream/master -u -- "*.py" | flake8 --diff`` might work as an alternative.)
 - [x] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=h1) Report
> Merging [#16897](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/8d0c025a4584c0f2d412d060c30fe459dc90b53b?src=pr&el=desc) will **decrease** coverage by `0.04%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16897/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16897      +/-   ##
==========================================
- Coverage   91.02%   90.98%   -0.05%     
==========================================
  Files         161      161              
  Lines       49303    49305       +2     
==========================================
- Hits        44878    44859      -19     
- Misses       4425     4446      +21
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.75% <100%> (-0.03%)` | :arrow_down: |
| #single | `40.19% <0%> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/indexing.py](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhpbmcucHk=) | `93.93% <100%> (+0.01%)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.23% <0%> (-1.82%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.75% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16897?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/16897?src=pr&el=footer). Last update [8d0c025...fc20f32](https://codecov.io/gh/pandas-dev/pandas/pull/16897?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 can you rebase and update will do later today thanks!