Pin .NET version to 5.0.x

Author: gsvgit

.github/workflows/build-on-push.yml

@@ -76,8 +76,10 @@ jobs:
 
       - uses: actions/checkout@v1
 
-      - name: Setup .NET Core
+      - name: Setup .NET
         uses: actions/setup-dotnet@v1
+        with:
+          dotnet-version: '5.0.x'
 
       - name: Build
         run: |