new language: Swift

[aldy505]

Add Swift as a supported language to detect

Learn swift here:

• https://www.swift.org/getting-started/
• https://learnxinyminutes.com/docs/swift/
• https://www.tutorialspoint.com/swift/index.htm

Some test cases:

• https://rosettacode.org/wiki/Monte_Carlo_methods#Swift
• https://rosettacode.org/wiki/Sorting_algorithms/Heapsort#Swift
• https://rosettacode.org/wiki/Sorting_algorithms/Quicksort#Swift
• https://rosettacode.org/wiki/Sorting_algorithms/Merge_sort#Swift
• https://rosettacode.org/wiki/Sorting_algorithms/Selection_sort#Swift
• https://rosettacode.org/wiki/Attractive_numbers#Swift
• https://rosettacode.org/wiki/Sorting_algorithms/Bubble_sort#Swift
• https://rosettacode.org/wiki/FizzBuzz#Swift
• https://rosettacode.org/wiki/Happy_numbers#Swift
• https://github.com/sindresorhus/Gifski/blob/main/Gifski/App.swift
• https://rosettacode.org/wiki/Guess_the_number#Swift
• https://rosettacode.org/wiki/Hello_world/Text#Swift
• https://github.com/sindresorhus/Plash/blob/main/Plash/Website.swift