Add JWSETKit

[amosavian]

• Project Name: JWSETKit
• Project URL: https://github.com/amosavian/JWSETKit
• Project Description: A full-featured Swift library for JOSE standards with first-class support for CryptoKit keys, providing JWS, JWT, and JWE with signing, encryption, and JWK key management.
• Why it should be added to awesome-swift: A library that hash extensive support of JOSE standard in Swift
• At least 15 stars (GitHub project)
• Support Swift 5
• Updated contents.json instead of README
• Lib is fully open sourced, written in Swift and not a wrapper over compiled lib
• Description does not say "written in Swift" or variant 🤓

[vpeschenkov]

@amosavian thanks!