Updates project to Swift 6.

-Fixes #39 thanks @stuartcamerondeakin 👏

Swift Package Manager is now the official way to integrate KeyboardLayoutGuide 🎉
Other package managers (Carthage and Cocoapods) are now deprecated in favour of the official way.

• Improves the api for using both safeArea and no safeArea with keyboardLayoutGuideNoSafeArea #28
• Fixes an animation glitch happening with a secured Textfield #32
• Builds pre-built framework with Xcode 11.3

Big thanks to @EfraimB & @abekert for this release 👏 🎉

• Builds with Xcode 11 & Swift 5.1

• Adds SPM support (thanks to @dstranz)
• Adds opting out from default safe Area (Thanks to @moyerr)

Thanks @numen31337 & @xzeror for the release

• Migrate to Swift 4.2 & Xcode 10 - Courtesy of @thomas-sivilay 🚀

Kudos to @ali312 for finding and fixing a nasty iPad slide over bug 👍

Fixes iOS 11 bug where keyboardWillChangeFrame is not called