Improve pre-commit workflow (#2602)

* feat: add `isort` to `pre-commit`

* ci: skip `__init__.py` file for `isort`

* ci: make `isort` mandatory in lint pipeline

* docs: add a section on Git hooks

* ci: check isort diff

* fix: isort from master branch

* docs: add pre-commit badge

* ci: update black + bandit versions

* feat: add PR template

* refactor: PR template

* ci: remove bandit

* docs: add Black badge

* ci: try to remove all `|| true` statements

* ci: remove lint_python job

- Remove `lint_python` CI job
- Move `pyupgrade` job to `pre-commit` workflow

* fix: avoid messing with typing

* docs: add a note on running `pre-cpmmit` manually

* ci: apply `pre-commit` to the whole codebase

gym/spaces/space.py

@@ -1,20 +1,11 @@
 from __future__ import annotations
 
-from typing import (
-    TypeVar,
-    Generic,
-    Optional,
-    Sequence,
-    Iterable,
-    Mapping,
-    Type,
-)
+from typing import Generic, Iterable, Mapping, Optional, Sequence, Type, TypeVar
 
 import numpy as np
 
 from gym.utils import seeding
 
-
 T_cov = TypeVar("T_cov", covariant=True)