Adding testcase for quartile performed on a timestamp column group by ( closes #33168 )
Have added a testcase for quartile performed on a timestamp column group by. This change closes #33168

Hello @dannyi96! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:



There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2022-07-02 13:07:20 UTC This is my first open source PR 🙂 any & all feedback is most welcome. 

Was wondering if one testcase would suffice here or we can add more by trying different inputs & its expected values ( similar to those above using `@pytest.mark.parametrize` )

 Looks pretty good. The code checks are failing though https://github.com/pandas-dev/pandas/runs/7156494708?check_suite_focus=true thanks @mroeschke, have corrected the code style & looks like the code checks have passed now thanks @dannyi96 