Fix CI: Add netstandard (winui 0) to sign and release matrices

The package job creates artifacts for winui [0, 2, 3], but sign and release jobs only processed [2, 3]. This caused netstandard-only packages like Extensions.DependencyInjection to be built but never signed or released to NuGet.org.

The sign and release jobs were added by copying from mainline Windows Community Toolkit, which doesn't have netstandard-only components. This PR updates both matrices to match Labs' package job requirements.

Author: Arlodotexe

.github/workflows/build.yml

@@ -391,7 +391,7 @@ jobs:
     strategy:
       fail-fast: false # prevent one matrix pipeline from being cancelled if one fails, we want them both to run to completion.
       matrix:
-        winui: [2, 3]
+        winui: [0, 2, 3]
 
     steps:
       - name: Install .NET SDK v${{ env.DOTNET_VERSION }}
@@ -456,7 +456,7 @@ jobs:
     strategy:
       fail-fast: false # prevent one matrix pipeline from being cancelled if one fails, we want them both to run to completion.
       matrix:
-        winui: [2, 3]
+        winui: [0, 2, 3]
 
     steps:
       - name: Install .NET SDK v${{ env.DOTNET_VERSION }}