Update ci.yml

Author: gruve-p

.github/workflows/ci.yml

@@ -231,7 +231,7 @@ jobs:
           name: electrum-grs-${{ github.sha }}-android-x86_64
 
   macos:
-    runs-on: macos-latest
+    runs-on: macos-14
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}
@@ -240,7 +240,7 @@ jobs:
           python-version: 3.12.10
       - uses: maxim-lobanov/setup-xcode@v1
         with:
-          xcode-version: 16.4.0
+          xcode-version: 15.0.1
       - name: Compile OSX dmg
         run: ./contrib/osx/make_osx.sh
       - name: Upload Artifact