TST: catch some test warnings
I get a hundred and change warnings locally when I run the test suite, am surprised the npdev build isn't failing on these.  This gets a handful of them.
Thanks @jbrockmendel (npdev build only raises on DeprecationWarning not FutureWarning) > npdev build only raises on DeprecationWarning not FutureWarning

Has it always been like this?  I thought we checked that we checked for FutureWarnings to make sure we weren't issuing any accidentally (e.g. ATM we issue some in fillna that we shouldn't bc we are using deprecated usage) Ah looks like I made the filter more narrow because numpy was propagating a distutils warning too? https://github.com/pandas-dev/pandas/pull/46767