 TST #24444 converting Period to Timestamp
I've tested intervals `ms`, `s` and `min`.
Note: the test raises an error for `ms` on v1.0.3, but is successful on master
Note: I did not choose to close this issue has the test fail for `ns` unit

[ ] #24444
[ 1 ] tests added / passed
[ x ] passes `black pandas`
[ x ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
