Add a pre-commit configuration to enforce basic file hygiene.

.github/workflows/pre-commit.yml

@@ -0,0 +1,24 @@
+# SPDX-FileCopyrightText: Copyright (c) 2019 Anthony Sottile
+#
+# SPDX-License-Identifier: MIT
+
+name: pre-commit
+
+on:
+  pull_request:
+  push:
+    branches: [master]
+
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - uses: actions/setup-python@v1
+    - name: set PY
+      run: echo "::set-env name=PY::$(python -c 'import hashlib, sys;print(hashlib.sha256(sys.version.encode()+sys.executable.encode()).hexdigest())')"
+    - uses: actions/cache@v1
+      with:
+        path: ~/.cache/pre-commit
+        key: pre-commit|${{ env.PY }}|${{ hashFiles('.pre-commit-config.yaml') }}
+    - uses: pre-commit/action@v1.1.0

.pre-commit-config.yaml

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+# SPDX-FileCopyrightText: 2020 Diego Elio Pettenò
+#
+# SPDX-License-Identifier: Unlicense
+
+repos:
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.3.0
+    hooks:
+    -   id: check-yaml
+    -   id: end-of-file-fixer
+        exclude: '^(tests/.*\.exp|tests/cmdline/.*|tests/.*/data/.*)'
+    -   id: trailing-whitespace
+        exclude: '^(tests/.*\.exp|tests/cmdline/.*|tests/.*/data/.*)'