fix #28926 mypy error in pandas\tests\arrays\test_array.py 
- [ ] xref #28926
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

lgtm @simonjayhawkins  Was (accidentally) also looking into this fix. However, I believe this is also the fix for:
* _pandas\tests\arrays\test_period.py_
```bash
pandas\tests\arrays\test_period.py:245: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
```
* _pandas\tests\test_base.py_
```bash
pandas\tests\test_base.py:1312: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\test_base.py:1354: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
```

This implies the entries for both of these files should also be removed from setup.cfg @yogendrasoni in merging master the section in setup.cfg for pandas\tests\arrays\test_period.py was reinstated. can you remove. Thanks @yogendrasoni 