fix error when pushing the nuget package to nuget.org

The push worked but the build failed with error:
 "Your package was pushed. error: File does not exist (true)."

According to this (not tested), the fix is to remove "true"
NuGet/Home#11601 (comment)

Author: pmiossec

.github/workflows/release_plugin.yml

@@ -48,4 +48,4 @@ jobs:
     - name: Push to Nuget.org nuget feed
       run: |
         cd "src/${{ github.event.repository.name }}/bin/Release"
-        dotnet nuget push *.nupkg -k ${{ secrets.NUGET_PUSH_TOKEN }} -s https://api.nuget.org/v3/index.json -n true
+        dotnet nuget push *.nupkg -k ${{ secrets.NUGET_PUSH_TOKEN }} -s https://api.nuget.org/v3/index.json -n