Fix code analysis action

Author: angularsen

.github/workflows/codeql-analysis.yml

@@ -39,6 +39,11 @@ jobs:
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
+    
+    # .NET 6 is used in CodeGen project.
+    - uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: '6.0.x'
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL