Add pre-commit workflow

Use pre-commit to enforce some of our checks on PRs

Signed-off-by: Joe Block <jpb@unixorn.net>

.github/workflows/pre-commit.yml

@@ -0,0 +1,14 @@
+name: pre-commit
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-python@v3
+    - uses: pre-commit/action@v3.0.0

.pre-commit-config.yaml

@@ -0,0 +1,20 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.4.0
+    hooks:
+      - id: check-merge-conflict
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+      - id: forbid-submodules
+      - id: mixed-line-ending
+  - repo: https://github.com/igorshubovych/markdownlint-cli
+    rev: v0.35.0
+    hooks:
+      - id: markdownlint-fix
+        args: ["--ignore", "LICENSE.md"]
+  - repo: https://github.com/thlorenz/doctoc
+    rev: v2.2.0
+    hooks:
+      - id: doctoc
+        args: ["--update-only"]