Update cs-build-project.yml

Change dotnet-version to 6.0.x here too

Author: JoeStrout

.github/workflows/cs-build-project.yml

@@ -18,7 +18,7 @@ jobs:
 
       - uses: actions/setup-dotnet@v2
         with:
-          dotnet-version: 7.0.x
+          dotnet-version: 6.0.x
 
       - name: Build
         run: dotnet build -c Release