ci: Add .NET setup to CodeQL GitHub Actions workflow

Autobuild doesn't install .NET 8 and .NET 9, which is required for this kind of multi-targeting.

Author: hangy

.github/workflows/codeql.yml

@@ -40,6 +40,11 @@ jobs:
         with:
           fetch-depth: 0
 
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          global-json-file: global.json
+
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v3