fix: Revert to langversion 10.0

src/Uno.UITest.Puppeteer/Uno.UITest.Selenium.csproj

@@ -4,7 +4,7 @@
 		<TargetFrameworks>net47;net6.0</TargetFrameworks>
 		<IsTestProject>false</IsTestProject>
 		<GeneratePackageOnBuild Condition="'$(Configuration)'=='Release'">true</GeneratePackageOnBuild>
-		<LangVersion>11.0</LangVersion>
+		<LangVersion>10.0</LangVersion>
 	</PropertyGroup>
 
 	<PropertyGroup>