ci: bump ci to macos-15

Author: kazo0

build/workflow/stage-build-ios.yml

@@ -20,7 +20,7 @@ jobs:
         CI_Build: true
 
   pool:
-    vmImage: 'macOS-14'
+    vmImage: 'macOS-15'
 
   variables:
   - group: unoplatform.apple.ios.appstore.distribution
@@ -119,7 +119,7 @@ jobs:
         CI_Build: true
 
   pool:
-    vmImage: 'macOS-14'
+    vmImage: 'macOS-15'
 
   steps:
   - template: templates/dotnet-workload-install-mac.yml

build/workflow/stage-uitests-android.yml

@@ -43,7 +43,7 @@
         SAMPLEAPP_PACKAGE_NAME: uno.platform.toolkit
 
   pool:
-    vmImage: 'macOS-14'
+    vmImage: 'macOS-15'
 
   steps:
   - checkout: self

build/workflow/stage-uitests-ios.yml

@@ -36,7 +36,7 @@
         SAMPLEAPP_ARTIFACT_NAME: ios-winui-uitest-build
 
   pool:
-    vmImage: 'macOS-14'
+    vmImage: 'macOS-15'
 
   steps:
   - checkout: self