[ci] remove some pre-commit hooks, add flak8

.flake8

@@ -0,0 +1,7 @@
+[flake8]
+max-line-length = 120
+ignore =
+       # whitespace before ':'
+       E203
+       # Line break before binary operator
+       W503

.pre-commit-config.yaml

@@ -10,20 +10,11 @@ repos:
       - id: check-case-conflict
       - id: check-docstring-first
       - id: check-merge-conflict
-      - id: check-toml
       - id: check-yaml
       - id: debug-statements
       - id: end-of-file-fixer
-      - id: forbid-new-submodules
       - id: mixed-line-ending
       - id: trailing-whitespace
-  - repo: https://github.com/pre-commit/pygrep-hooks
-    rev: v1.7.0
-    hooks:
-      - id: python-check-mock-methods
-      - id: python-no-eval
-      - id: python-no-log-warn
-      - id: python-use-type-annotations
   - repo: https://github.com/Lucas-C/pre-commit-hooks
     rev: v1.1.9
     hooks:
@@ -37,7 +28,7 @@ repos:
     hooks:
       - id: blacken-docs
         additional_dependencies: [ black==20.8b1 ]
-  - repo: https://github.com/asottile/setup-cfg-fmt
+  - repo: https://gitlab.com/PyCQA/flake8
-    rev: v1.15.1
+    rev: 3.8.4
     hooks:
-      - id: setup-cfg-fmt
+      - id: flake8