Adjust TargetFramework declaration to support multiple values.

Author: Arlodotexe

ProjectHeads/App.Head.Wasm.props

@@ -1,7 +1,7 @@
 <Project>
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>$(WasmHeadTargetFramework)</TargetFramework>
+    <TargetFramework>$(WasmHeadTargetFramework.Split(';')[0])</TargetFramework>
   </PropertyGroup>
 
   <Import Project="$(MSBuildThisFileDirectory)\App.Head.Uno.props" />