Update ci.yml

Author: mrahhal

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.401
+        dotnet-version: 6.0.100
 
     - name: Build
       run: ./build