Update dotnet-core.yml

Author: kccarter76

.github/workflows/dotnet-core.yml

@@ -11,7 +11,7 @@ jobs:
 
     runs-on: ubuntu-latest
     env:
-      VERSION: 4.3.0.alpha.1
+      VERSION: 4.3.0-alpha.1
 
     steps:
     - uses: actions/checkout@v2