Update dependencies from https://github.com/dotnet/winforms build 20211222.8 (#5869)

[main] Update dependencies from dotnet/winforms

eng/Version.Details.xml

 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
   <ProductDependencies>
-    <Dependency Name="Microsoft.Private.Winforms" Version="7.0.0-alpha.1.21622.6">
+    <Dependency Name="Microsoft.Private.Winforms" Version="7.0.0-alpha.1.21622.8">
       <Uri>https://github.com/dotnet/winforms</Uri>
-      <Sha>0f430be707190239f8475a74c207142a80291d40</Sha>
+      <Sha>a8da3b57279985a7f1dbc471e17f2f48c236552e</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.Dotnet.WinForms.ProjectTemplates" Version="7.0.0-alpha.1.21622.6">
+    <Dependency Name="Microsoft.Dotnet.WinForms.ProjectTemplates" Version="7.0.0-alpha.1.21622.8">
       <Uri>https://github.com/dotnet/winforms</Uri>
-      <Sha>0f430be707190239f8475a74c207142a80291d40</Sha>
+      <Sha>a8da3b57279985a7f1dbc471e17f2f48c236552e</Sha>
     </Dependency>
     <Dependency Name="System.CodeDom" Version="7.0.0-alpha.1.21606.7" CoherentParentDependency="Microsoft.Private.Winforms">
       <Uri>https://github.com/dotnet/runtime</Uri>

eng/Versions.props

@@ -9,7 +9,7 @@
   </PropertyGroup>
   <!-- NuGet Package Versions -->
   <PropertyGroup>
-    <MicrosoftPrivateWinformsVersion>7.0.0-alpha.1.21622.6</MicrosoftPrivateWinformsVersion>
+    <MicrosoftPrivateWinformsVersion>7.0.0-alpha.1.21622.8</MicrosoftPrivateWinformsVersion>
   </PropertyGroup>
   <!-- Packages that come from https://github.com/dotnet/coreclr -->
   <PropertyGroup>