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

tests/wrappers/test_frame_stack.py

@@ -3,6 +3,7 @@ import pytest
 pytest.importorskip("gym.envs.atari")
 
 import numpy as np
+
 import gym
 from gym.wrappers import FrameStack
 
@@ -39,7 +40,7 @@ def test_frame_stack(env_id, num_stack, lz4_compress):
     dup_obs = dup.reset(seed=0)
     assert np.allclose(obs[-1], dup_obs)
 
-    for _ in range(num_stack ** 2):
+    for _ in range(num_stack**2):
         action = env.action_space.sample()
         dup_obs, _, _, _ = dup.step(action)
         obs, _, _, _ = env.step(action)