ci: add Python 3.14 in the unit test #617

Job	Run time
flutter_e2e_test (ubuntu-latest, flutter-android)	6m 26s
ios_test (test/functional/ios/safari_tests.py, func_test_ios1)	17m 58s
flutter_e2e_test (macos-15, flutter-ios)	58m 43s
android_test (test/functional/android/appium_service_tests.py test/functional/android/chrome_test...	4m 6s
	1h 27m 13s

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