publish in netstandard2.1 framework

Author: Lordfirespeed

.github/workflows/publish.yml

@@ -109,4 +109,4 @@ jobs:
         env:
           TCLI_AUTH_TOKEN: ${{ secrets.THUNDERSTORE_API_TOKEN }}
         run: |
-          dotnet build -c Release -target:ThunderstorePublish
+          dotnet build -c Release -f netstandard2.1 -target:ThunderstorePublish