Remove System.ValueTuple package dependency from net472 target framework. (#2739)

Co-authored-by: Rivera, Mariano <[email protected]>

Author: Rivsoft

src/ReactiveUI/ReactiveUI.csproj

@@ -37,12 +37,15 @@
 
   <ItemGroup Condition=" $(TargetFramework.StartsWith('net4')) ">
     <Compile Include="Platforms\net4\**\*.cs" />
-    <PackageReference Include="System.ValueTuple" Version="4.5.0" />
     <Reference Include="System.Windows" />
     <Reference Include="System.Windows.Forms" />
     <Reference Include="WindowsBase" />
   </ItemGroup>
 
+  <ItemGroup Condition=" $(TargetFramework.StartsWith('net46')) ">
+    <PackageReference Include="System.ValueTuple" Version="4.5.0" />
+  </ItemGroup>
+
   <ItemGroup Condition=" $(TargetFramework.StartsWith('net46')) or $(TargetFramework) == 'net5.0-windows' ">
     <Compile Include="Platforms\net4Desktop\**\*.cs" />
   </ItemGroup>