Update dotnet-core-release.yml

testing a tag regex to match tagged releases

Author: kccarter76

.github/workflows/dotnet-core-release.yml

@@ -4,7 +4,7 @@ name: .Net Standard Release
 on:
   push:
     tags: 
-      - v*-alpha.*
+      - 'v[0-9].[0-9].[0-9]-[alpha|beta].*'
     branches:
       - release/*