Do shallow clones for sonar

.github/workflows/main.yml

@@ -24,6 +24,8 @@ jobs:
     
       - name: Checkout (without submodules)
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
 
       - name: Set up JDK 11 (for Sonar)
         uses: actions/setup-java@v1