Add other platforms into CI check.

.github/workflows/ci.yaml

@@ -19,13 +19,18 @@ jobs:
     runs-on: macOS-latest
     strategy:
       matrix:
-        # target: ['macOS', 'iOS', 'tvOS', 'watchOS']
-        target: ['macOS']
+        target: ['macOS', 'iOS', 'tvOS', 'watchOS']
         include:
             - briefcase-run-args:
+            - run-tests: false
+
+            - target: macOS
+              run-tests: true
+
+            - target: iOS
+              briefcase-run-args: ' -d "iPhone SE (3rd generation)"'
+              run-tests: true
 
-            # - target: iOS
-            #   briefcase-run-args: ' -d "iPhone SE (3rd generation)"'
     steps:
     - uses: actions/checkout@v4
 
@@ -36,29 +41,34 @@ jobs:
         echo "PYTHON_VER=${PYTHON_VER}" | tee -a ${GITHUB_OUTPUT}
 
     - name: Set up Python
+      if: matrix.run-tests
       uses: actions/setup-python@v4.7.1
       with:
         # Appending -dev ensures that we can always build the dev release.
         # It's a no-op for versions that have been published.
         python-version: ${{ steps.config-vars.outputs.PYTHON_VER }}-dev
 
     - name: Build ${{ matrix.target }}
+      if: matrix.run-tests
       run: |
         # Do the build for the requested target.
         make ${{ matrix.target }}
 
     - uses: actions/checkout@v4
+      if: matrix.run-tests
       with:
         repository: beeware/Python-support-testbed
         path: Python-support-testbed
         ref: py3.13-support
 
     - name: Install dependencies
+      if: matrix.run-tests
       run: |
         # Use the development version of Briefcase
         python -m pip install git+https://github.com/beeware/briefcase.git
 
     - name: Run support testbed check
+      if: matrix.run-tests
       working-directory: Python-support-testbed
       # TODO - remove the template_branch option.
       run: briefcase run ${{ matrix.target }} Xcode --test ${{ matrix.briefcase-run-args }} -C support_package=\'../dist/Python-${{ steps.config-vars.outputs.PYTHON_VER }}-${{ matrix.target }}-support.custom.tar.gz\' -C template_branch=\'framework-lib\'