TST7337: Try to resolve windows test failures.
This change fixes broken tests on windows following `ENH: Support dateutil timezones`

closes #7337 

Closing as change being merged already.
 ha....didn't merge yet....is this exactly the same?
 yes, it's just that single commit.
 merged via https://github.com/pydata/pandas/commit/662944666f770e537dfc4a71bb0c1a2c5e89140c
