Remove parentheses around multiple exception types in `except` and `except*` without `as`. (#4720)

* Remove parentheses around multiple exception types in `except` and `except*` when not using the `as` clause. (#4678)

* Add Changelog Entry

* Add Unparenthesized Except Tuple Detection.

* Add tests for `except*`.

* Oops! Wrong Version.

* Fix function `supports_feature` to return False when `target_versions`  is empty. [skip news] (#4726)

* Fix function `supports_feature` to return False when `target_versions` is empty.

* supports_feature: raise ValueError if target_versions is empty

* Simplify conditional logic for removing except type parens.