Update dotnet versions

Author: laurynas

.github/workflows/main.yml

@@ -6,8 +6,14 @@ jobs:
     strategy:
       matrix:
         dotnet-version:
-          - '2.1'
           - '2.2'
+          - '3.0'
+          - '3.1'
+          - '5.0'
+          - '6.0'
+          - '7.0'
+          - '8.0'
+          - '9.0'
     name: .NET ${{ matrix.dotnet-version }} sample
     steps:
       - uses: actions/checkout@v3