net 6.0 is enough

Author: Spacefish

.github/workflows/build.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        dotnet-version: ['3.1.x', '6.0.x']
+        dotnet-version: ['6.0.x']
     steps:
       - uses: actions/checkout@v3
       - name: Setup .NET Core SDK ${{ matrix.dotnet-version }}