push.yml: build using Xcode v26.4.1 on macOS

Author: stephengold

.github/workflows/push.yml

@@ -68,6 +68,9 @@ jobs:
           java-version: 21
       - uses: actions/checkout@v6
       - uses: gradle/actions/setup-gradle@v6
+      - uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: '26.4.1'
       - run: |
           ./gradlew -Pbt=Debug -Pflavor=Dp -Ptarget=Linux64 -Ptool=gcc run build install \
             --console=plain \
@@ -99,6 +102,9 @@ jobs:
           java-version: 21
       - uses: actions/checkout@v6
       - uses: gradle/actions/setup-gradle@v6
+      - uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: '26.4.1'
       - run: |
           ./gradlew -Pbt=Release -Pflavor=Sp -Ptarget=MacOSX64 install \
             --console=plain \