ci: add CodeQL workflow for Ruby

Author: ronaldtse

.github/workflows/codeql.yml

@@ -0,0 +1,27 @@
+name: codeql
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  schedule:
+    - cron: "0 0 * * 0"  # weekly
+
+permissions:
+  actions: read
+  contents: read
+  security-events: write
+
+jobs:
+  analyze:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ruby]
+    steps:
+      - uses: actions/checkout@v7
+      - uses: github/codeql-action/init@v3
+        with:
+          languages: ${{ matrix.language }}
+      - uses: github/codeql-action/analyze@v3