Use new .NET things (#2264)

Author: mattleibow

scripts/azure-pipelines-variables.yml

@@ -15,8 +15,8 @@ variables:
   MONO_VERSION_LINUX: ''
   XCODE_VERSION: 13.2.1
   VISUAL_STUDIO_VERSION: '17/pre'
-  DOTNET_VERSION_PREVIEW: '6.0.400'
-  DOTNET_WORKLOAD_SOURCE: 'https://maui.blob.core.windows.net/metadata/rollbacks/6.0.513.json'
+  DOTNET_VERSION_PREVIEW: '6.0.401'
+  DOTNET_WORKLOAD_SOURCE: 'https://maui.blob.core.windows.net/metadata/rollbacks/6.0.540.json'
   CONFIGURATION: 'Release'
   DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
   THROW_ON_TEST_FAILURE: true