[python] Adding type ignores for dependencies without type support

[TGooch44]

Adds mypy ignores for pytz and dateutil

[TGooch44]

@jun-he @rymurr I opened this PR to add some ignores on pytz and dateutil that are currently throwing linter errors on tox. Let me know if this looks ok, or if you'd prefer to handle it another way.

[rymurr]

Hey @TGooch44 any reason to not add types-python-dateutil and types-pytz to the test env dependencies?

I believe mypy recently changed its default behaviour. Previously it silently auto-downloaded these packages.

[TGooch44]

Sure, my thinking was that since these both have pretty limited usage, I didn't want to add in more deps, but I guess not really a big deal to add in type stubs.

[rymurr]

I personally prefer deps over # noqa but im not so bothered.

[TGooch44]

I personally prefer deps over # noqa but im not so bothered.

Given that these deps are only for mypy, I think you're right that it is better just to add them in over using ignores.