STYLE: fail on pd.testing direct usage

[jreback]

pd.testing.assert_series_equal(result, expected)

should fail style checks, rather we want tm.assert_series_equal

we need to update any usages in the codebase as well as add this to the pre-commit checks.

[inspurwusixuan]

Hi @jreback, can I take this? :)

[weikhor]

Hi @jreback Please give example of fail style meaning so I can proceed on which part of code I need to make change. I newbie on contribution. Please assist Thank

[cjlynch278]

Hello, I'm going to try to fix this issue. I'll submit a pull request linking the issue if I'm able to complete it within the next week, otherwise I'll post an update here