Fix CI: Pin to windows-2022 runners

Windows 2025 runners removed all preinstalled SDKs except latest,
breaking all CI builds. Pin to windows-2022 to restore SDK availability.

Related: CommunityToolkit/Labs-Windows#741

Author: Arlodotexe

.github/workflows/build.yml

@@ -25,7 +25,7 @@ env:
 jobs:
   # This workflow contains a single job called "Xaml-Style-Check"
   Xaml-Style-Check:
-    runs-on: windows-latest
+    runs-on: windows-2022
 
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
@@ -89,7 +89,7 @@ jobs:
 
   # Test job to build the project template
   project-template:
-    runs-on: windows-latest
+    runs-on: windows-2022
     env:
       HEADS_DIRECTORY: tooling/ProjectHeads
       PROJECT_DIRECTORY: tooling/ProjectTemplate
@@ -139,7 +139,7 @@ jobs:
 
   # Test job to build a single experiment to ensure our changes work for both our main types of solutions at the moment
   new-experiment:
-    runs-on: windows-latest
+    runs-on: windows-2022
 
     strategy:
       fail-fast: false # prevent one matrix pipeline from being cancelled if one fails, we want them all to run to completion.