Update release.yaml

Set GeneratePackageOnBuild=false due to an issue where when true it does not build. dotnet/sdk#3473 (comment)

Author: alex-davies

.github/workflows/release.yaml

@@ -17,6 +17,6 @@ jobs:
       with:
         dotnet-version: 5.0.*
     - name: Pack
-      run: dotnet pack --output ./artifacts --configuration Release -p:Version=$RELEASE_VERSION
+      run: dotnet pack --output ./artifacts --configuration Release -p:GeneratePackageOnBuild=false -p:Version=$RELEASE_VERSION
     - name: Publish packages
       run: dotnet nuget push ./artifacts/**.nupkg --source nuget.org --api-key ${{secrets.NUGET_TOKEN}}