Rewind SDK version for reunion (#8092)

* Use older SDK for the purpose of Reunion projection

* Change files

* 18362 it is

* TFM 18362, WTFV 17763

* WTFV 18362

change/react-native-windows-56b9c874-cffa-4b25-8e10-8414939d84c3.json

@@ -0,0 +1,7 @@
+{
+  "type": "prerelease",
+  "comment": "Use older SDK for the purpose of Reunion projection",
+  "packageName": "react-native-windows",
+  "email": "asklar@microsoft.com",
+  "dependentChangeType": "patch"
+}

vnext/ExperimentalFeatures.props

@@ -1,5 +1,6 @@
 <Project>
   <PropertyGroup Condition="'$(SolutionName)'=='Microsoft.ReactNative.ProjectReunion'">
     <UseWinUI3>true</UseWinUI3>
+    <WindowsTargetPlatformVersion>10.0.18362.0</WindowsTargetPlatformVersion>
   </PropertyGroup>
 </Project>

vnext/Microsoft.ReactNative.ProjectReunion/Microsoft.ReactNative.ProjectReunion.csproj

@@ -1,6 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net5.0-windows10.0.19041.0</TargetFramework>
+      <!-- Ideally we target 17763, but we can't do that 
+      until https://github.com/microsoft/ProjectReunion/issues/921 is fixed -->
+    <TargetFramework>net5.0-windows10.0.18362.0</TargetFramework>
     <Platforms>x64</Platforms>
   </PropertyGroup>
 

vnext/Scripts/Microsoft.ReactNative.ProjectReunion.nuspec

@@ -17,9 +17,7 @@
       <group targetFramework=".NETCoreApp3.0" />
       <group targetFramework="UAP10.0" />
       <group targetFramework=".NETFramework4.6" />
-      <group targetFramework="net5.0">
-        <dependency id="Microsoft.Windows.CsWinRT" version="1.3.0" exclude="Build,Analyzers" />
-      </group>
+      <group targetFramework="net5.0" />
     </dependencies>
   </metadata>
   <files>