COMPAT-18589: Supporting axis in Series.rename
- [x] closes #18589
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18923?src=pr&el=h1) Report
> Merging [#18923](https://codecov.io/gh/pandas-dev/pandas/pull/18923?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/569bc7a35c06ef8eb9a121ca983ba8951399a124?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18923/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/18923?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18923      +/-   ##
==========================================
+ Coverage   91.58%   91.59%   +<.01%     
==========================================
  Files         150      150              
  Lines       48806    48809       +3     
==========================================
+ Hits        44701    44706       +5     
+ Misses       4105     4103       -2
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.96% <100%> (ø)` | :arrow_up: |
| #single | `41.73% <66.66%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18923?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/18923/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `95.94% <100%> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18923/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `83.85% <0%> (+0.2%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18923?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/18923?src=pr&el=footer). Last update [569bc7a...1794b98](https://codecov.io/gh/pandas-dev/pandas/pull/18923?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks!