Merge pull request clean-css#59 from XhmikosR/codeql

Add CodeQL GitHub action.

Author: jakubpawlowicz

.github/workflows/codeql.yml

@@ -0,0 +1,34 @@
+name: "CodeQL"
+
+on:
+  push:
+    branches:
+      - master
+      - "!dependabot/**"
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches:
+      - master
+  schedule:
+    - cron: "0 2 * * 5"
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      # Initializes the CodeQL tools for scanning.
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v1
+        with:
+          languages: "javascript"
+
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@v1
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v1