Update Xcode versions to fix CI (#87)

.github/workflows/app_check_core.yml

@@ -16,14 +16,12 @@ jobs:
       matrix:
         # TODO: macos tests are blocked by https://github.com/erikdoe/ocmock/pull/532
         target: [ios, tvos, macos --skip-tests, watchos]
-        os: [macos-13, macos-14, macos-15]
+        os: [macos-15, macos-26]
         include:
-          - os: macos-13
-            xcode: Xcode_15.2
-          - os: macos-14
-            xcode: Xcode_15.4
           - os: macos-15
-            xcode: Xcode_16.1
+            xcode: Xcode_16.4
+          - os: macos-26
+            xcode: Xcode_26.1
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v3

.github/workflows/check.yml

@@ -31,7 +31,7 @@ jobs:
     - name: Setup check
       run: |
         brew update
-        brew install clang-format@20
+        brew install clang-format@21
         brew install mint
         mint bootstrap