simplify setup dotnet (#1043)

.github/workflows/codeql-analysis.yml

@@ -25,18 +25,13 @@ jobs:
       with:
           fetch-depth: 0
 
-    - name: Setup dotnet SDK 3.1
+    - name: Setup dotnet
       uses: actions/setup-dotnet@v2
       with:
-        dotnet-version: '3.1.x'          
-    - name: Setup dotnet SDK 5
-      uses: actions/setup-dotnet@v2
-      with:
-        dotnet-version: '5.0.x'                
-    - name: Setup dotnet SDK 6
-      uses: actions/setup-dotnet@v2
-      with:
-        dotnet-version: '6.0.x'               
+        dotnet-version: |
+          3.1.x
+          5.0.x
+          6.0.x                     
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL