use 15?

Author: TingDaoK

.github/workflows/ci.yml

@@ -203,7 +203,7 @@ jobs:
         python .\aws-c-http\build\deps\aws-c-common\scripts\appverifier_ctest.py --build_directory .\aws-c-http\build\aws-c-http
 
   macos:
-    runs-on: macos-26
+    runs-on: macos-15
     strategy:
       fail-fast: false
       matrix:
@@ -220,7 +220,7 @@ jobs:
         ./builder build -p ${{ env.PACKAGE_NAME }} --cmake-extra=-DAWS_USE_APPLE_NETWORK_FRAMEWORK=${{ matrix.eventloop == 'dispatch_queue' && 'ON' || 'OFF' }}
 
   macos-x64:
-    runs-on: macos-26-large
+    runs-on: macos-15-large
     steps:
     - uses: aws-actions/configure-aws-credentials@v4
       with:
@@ -247,7 +247,7 @@ jobs:
         python3 builder.pyz build -p aws-c-http --cmake-extra=-DENABLE_LOCALHOST_INTEGRATION_TESTS=ON --config Debug
 
   localhost-test-macos:
-    runs-on: macos-26
+    runs-on: macos-15
     strategy:
       fail-fast: false
       matrix: