add gitleaks as credential scanner to actions

Author: Niklas Burchhardt

.github/workflows/main.yml

@@ -9,6 +9,21 @@ on:
       - main
 
 jobs:
+  gitleaks:
+    name: Secret Scanner
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0 # Gitleaks needs the full history to scan properly
+
+      - name: Run Gitleaks
+        uses: gitleaks/gitleaks-action@v3
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITLEAKS_LICENSE: ${{ secrets.GITLEAKS_LICENSE }}
+
   test:
     runs-on: ubuntu-latest