Do not explicitly install xcpretty
Do not explicitly install xcpretty

The `xcpretty-travis-formatter` gem depends on `xcpretty` so there is no need to run the gem install command twice.

c0unt0/XCDYouTubeKit,morrisirrom/XCDYouTubeKit,kumabook/XCDYouTubeKit,mingsai/XCDYouTubeVideoPlayerViewController,gshaviv/XCDYouTubeVideoPlayerViewController,itamaker/XCDYouTubeKit,0xced/XCDYouTubeKit,kumabook/XCDYouTubeKit,morrisirrom/XCDYouTubeKit,gshaviv/XCDYouTubeVideoPlayerViewController,0xced/XCDYouTubeKit,c0unt0/XCDYouTubeKit,mingsai/XCDYouTubeVideoPlayerViewController,mingsai/XCDYouTubeVideoPlayerViewController,creationst/XCDYouTubeKit,creationst/XCDYouTubeKit,gshaviv/XCDYouTubeVideoPlayerViewController,kumabook/XCDYouTubeKit,morrisirrom/XCDYouTubeKit,morrisirrom/XCDYouTubeKit,gshaviv/XCDYouTubeVideoPlayerViewController,twobitlabs/XCDYouTubeKit,morrisirrom/XCDYouTubeKit,kumabook/XCDYouTubeKit,gshaviv/XCDYouTubeVideoPlayerViewController,twobitlabs/XCDYouTubeKit,gshaviv/XCDYouTubeVideoPlayerViewController,creationst/XCDYouTubeKit,creationst/XCDYouTubeKit,c0unt0/XCDYouTubeKit,c0unt0/XCDYouTubeKit,mingsai/XCDYouTubeVideoPlayerViewController,twobitlabs/XCDYouTubeKit,0xced/XCDYouTubeKit,kumabook/XCDYouTubeKit,twobitlabs/XCDYouTubeKit,0xced/XCDYouTubeKit,itamaker/XCDYouTubeKit,kumabook/XCDYouTubeKit,c0unt0/XCDYouTubeKit