Fix Cs projects to require RS5

The Cs projects run down-level to RS5. They should not require Win11.

Author: jeffstall

Samples/Islands/DrawingIsland/DrawingCsTestApp/DrawingCsTestApp.csproj

@@ -10,7 +10,8 @@
     <Platforms>x64;ARM64;x86</Platforms>
 
     <!-- TODO: Why do we need to specify the explicit RIDs? -->   
-    <RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>
+    <RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>   
+    <SupportedOSPlatformVersion>10.0.17763.0</SupportedOSPlatformVersion>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">

Samples/Islands/DrawingIsland/DrawingIslandCsProjection/DrawingIslandCsProjection.csproj

@@ -19,6 +19,7 @@
 
     <!-- The CsWinRTGeneratedFilesDir property sets the output directory in which the projection source files are generated. This property is set to OutDir, defined in Directory.Build.props from the section above. -->
     <CsWinRTGeneratedFilesDir>$(OutDir)</CsWinRTGeneratedFilesDir>
+    <SupportedOSPlatformVersion>10.0.17763.0</SupportedOSPlatformVersion>
 
   </PropertyGroup>