Can we remove `__str__` methods on enums?

[l0b0]

A bunch of enums in the code base include this code:

def __str__(self) -> str:
    return str(self.value)

I'm not sure if these are useful, since we can get the same with Foo.BAR.value. A lot of them are not covered by tests either, which probably means they aren't used in production code.

[duckontheweb]

At one point I thought I had tried this and it caused a number of test failures, but that doesn't seem to be the case anymore (the only test failures are the ones that call str(SomeEnum.SOME_MEMBER)). I assumed originally that these were needed for JSON serialization, but that may not be true.

[l0b0]

Looking at the use cases for these methods, it appears there are a bunch of tests like self.assertEqual(str(VersionRelType.LATEST), "latest-version"). After changing these to self.assertEqual(VersionRelType.LATEST.value, "latest-version") we probably can get rid of them, since they are just testing a static value and not any functionality.