upload artifact v2 is released

Author: Alex McCool

.github/workflows/dotnetcore.yml

@@ -46,7 +46,7 @@ jobs:
     - name: Create nupkg
       run: dotnet pack --configuration Release src\ElasticSearch.Extensions.Logging\AM.Extensions.Logging.ElasticSearch.csproj
     - name: Upload nupkg
-      uses: actions/upload-artifact@v2-preview
+      uses: actions/upload-artifact@v2
       with:
         name: nupkg
         path: '**/AM.Extensions.Logging.ElasticSearch.*.nupkg'