ci: add CodeQL config

Author: eiri

.github/workflows/codeql.yml

@@ -0,0 +1,34 @@
+name: "CodeQL"
+on:
+  push:
+    branches: ['main']
+  pull_request:
+    branches: ['main']
+  schedule:
+  - cron: '00 4 * * 2'
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+    strategy:
+      fail-fast: false
+      matrix:
+        language: ['python']
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v3
+      with:
+        languages: ${{ matrix.language }}
+        config: |
+          paths-ignore:
+          - 'examples/snippets/**/*.py'
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v3
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v3
+      with:
+        category: "/language:${{matrix.language}}"