Workaround missing default system image for Android API level 36

Google hasn't published an AOSP version of the Android system image
for API level 36 yet:
https://issuetracker.google.com/issues/432143095

Temporarily switch to the Google APIs variant to workaround this
issue.

Author: emersion

.github/workflows/test.yml

@@ -192,12 +192,16 @@ jobs:
           echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' | sudo tee /etc/udev/rules.d/99-kvm4all.rules
           sudo udevadm control --reload-rules
           sudo udevadm trigger --name-match=kvm
-      - name: Run flutter test integration_test/webcrypto_test.dart -d android
+      - name: Run flutter test integration_test/webcrypto_test.dart -d gphone64
         uses: reactivecircus/android-emulator-runner@v2
         with:
           api-level: 36
+          # TODO: switch back to default once this is issue resolved:
+          # https://issuetracker.google.com/issues/432143095
+          target: google_apis
+          arch: x86_64
           working-directory: ./example
-          script: flutter test integration_test/webcrypto_test.dart -d android
+          script: flutter test integration_test/webcrypto_test.dart -d gphone64
   linux-coverage:
     name: Linux desktop / Chrome / Firefox (coverage)
     runs-on: ubuntu-latest