skip Release build in CI, try building latest .NET Framework as well

Author: bodewig

appveyor.yml

@@ -12,6 +12,7 @@ for:
   - matrix:
       only:
         - image: Visual Studio 2013
+        - image: Visual Studio 2022
     before_build:
       - appveyor DownloadFile https://dist.nuget.org/win-x86-commandline/v4.9.2/nuget.exe
       - appveyor DownloadFile https://raw.githubusercontent.com/appveyor/ci/master/scripts/nuget-restore.cmd
@@ -30,6 +31,7 @@ for:
         - image: Ubuntu2004
     before_build:
       - dotnet restore XMLUnit.NET.sln
+      - dotnet --version
     build:
       project: XMLUnit.NET.sln
     test_script:
@@ -43,7 +45,6 @@ install:
 
 configuration:
   - Debug
-  - Release
 
 matrix:
   fast_finish: true