Add pre-commit configuration and workflow

Add our standard suite of pre-commit checks, including linting and
formatting with ruff. Arrange to run these checks on pushes and
pull requests. Remove the pep8 target from tox configuration.

This includes a dependabot configuration to keep github action
versions up to date.

.github/dependabot.yaml

@@ -0,0 +1,10 @@
+# Set update schedule for GitHub Actions
+
+version: 2
+updates:
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      # Check for updates to GitHub Actions every week
+      interval: "weekly"

.github/workflows/precommit.yaml

@@ -0,0 +1,31 @@
+name: "Run pre-commit checks"
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  run-linters:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Configure caching
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pre-commit
+          key: precommit-${{ runner.os }}-${{ hashFiles('.pre-commit-config.yaml') }}
+
+      - name: Install pre-commit
+        run: |
+          pip install pre-commit
+
+      - name: Run linters
+        run: |
+          pre-commit run --all-files

.github/workflows/tests.yml

@@ -20,7 +20,5 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install tox
-      - name: Lint
-        run: tox -epep8
       - name: Unit Tests
         run: tox -epy3

.pre-commit-config.yaml

@@ -0,0 +1,27 @@
+repos:
+- repo: https://github.com/pre-commit/pre-commit-hooks
+  rev: v5.0.0
+  hooks:
+  - id: trailing-whitespace
+  - id: check-merge-conflict
+  - id: end-of-file-fixer
+  - id: check-added-large-files
+  - id: check-case-conflict
+  - id: check-json
+  - id: check-symlinks
+  - id: detect-private-key
+  - id: check-executables-have-shebangs
+
+- repo: https://github.com/adrienverge/yamllint.git
+  rev: v1.35.1
+  hooks:
+  - id: yamllint
+    files: \.(yaml|yml)$
+    types: [file, yaml]
+    entry: yamllint --strict
+
+- repo: https://github.com/astral-sh/ruff-pre-commit
+  rev: v0.9.1
+  hooks:
+  - id: ruff
+  - id: ruff-format

.yamllint.yaml

@@ -0,0 +1,10 @@
+extends: default
+rules:
+  line-length: disable
+  document-start: disable
+  indentation:
+    indent-sequences: whatever
+  hyphens:
+    max-spaces-after: 4
+  truthy:
+    check-keys: false