Update the Travis-CI environment to Xcode 11, because the test case need this
Update the Travis-CI environment to Xcode 11, because the test case need this

tualatrix/SDWebImage,dreampiggy/SDWebImage,awkward/SDWebImage,dreampiggy/SDWebImage,rs/SDWebImage,dreampiggy/SDWebImage,awkward/SDWebImage,awkward/SDWebImage