DEPR: Deprecate pandas/io/date_converters.py
- [x] closes #24518
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

@jreback addressed all your comments. Could you have a second look? this looks good can you merge master and ping on green. @jreback merged master; all checks in CI pass except two, due to a flaky test (see below)

`hypothesis.errors.Flaky: Hypothesis test_shift_across_dst(offset=<31 * MonthEnds>) produces unreliable results: Falsified on the first call but did not on a subsequent one` Reran CI, now everything passes @jreback updated doc, merged master and CI on green thanks @avinashpancham very nice!