Flake8-simplify

New rules:

* SIM910: dict.get(key, None) → dict.get(key)

Removed rules due to false-positives:

* SIM902: Positional-only parameters cannot be identified in the AST
* SIM908: Ensure that the assigned name is equal to the name in the if.test

* SIM104: Remove false-positives in case the loop is not a direct child of
an async function (147) by wyuenho

New rules:

* SIM902: Use keyword-argument instead of magic boolean
* SIM903: Use keyword-argument instead of magic number
* SIM907: Use Optional[Type] instead of Union[Type, None]
* SIM908: Use ".get" instead of "if X in dict: dict[X]"
* SIM909: Avoid reflexive assignments

Removed rules due to false-positives:

* SIM119: Hinting to dataclasses in a proper way is hard

Fixed false-positives:

* SIM108: Encourage the use of a terniary operator only when it is
actually possible
* SIM111: Recommending to use all/any only if there is no side-effect after
the for-loop
* SIM116: When a function is called, we cannot simply convert the
if-else block to a dictionary

Removed rules due to false-positives:

* SIM204: Use 'a >= b' instead of 'not (a < b)'
* SIM205: Use 'a > b' instead of 'not (a <= b)'
* SIM206: Use 'a <= b' instead of 'not (a > b)'
* SIM207: Use 'a < b' instead of 'not (a <= b)'

Fixed false-positives:

* SIM113: Use enumerate instead of manually incrementing a counter

Maintenance:

* Split a way-too-big module into smaller modules

Only distribute the `flake8_simplify` package. `0.18.0` did also distribute
the `tests` package which caused issues in some systems.