Migrate from sln to slnx (#705)

* Migrate from sln to slnx

* Update dotnet-ci

Author: Alirexaa

.github/workflows/dotnet-ci.yml

@@ -13,6 +13,7 @@ on:
       - Directory.Packages.props
       - ".github/workflows/**"
       - ".github/actions/**"
+      - "CommunityToolkit.Aspire.slnx"
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}