Update test.yml

Author: dragon7307

.github/workflows/test.yml

@@ -21,7 +21,12 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v3
       with:
-        dotnet-version: 9.0.x
+        dotnet-version: |
+                9.0.x
+                8.0.x
+                7.0.x
+                6.0.x
+        
     - name: Restore dependencies
       run: dotnet restore
     - name: Build