Adding ConnectableKit package to Libraries Category

[tugcanonbas]

• Project Name: ConnectableKit
• Project URL: https://github.com/tugcanonbas/connectable-kit
• Project Description: ConnectableKit is a Swift package for the Vapor framework that simplifies the response DTOs and JSON structures for API projects.
• Why it should be added to awesome-vapor: This package could be a valuable addition to the Awesome Vapor list because it simplifies the process of building responses in Vapor and can save developers a lot of time.
• Project has at least 15 stars (if it’s a GitHub project)
• Project supports at least Vapor 3
• Project supports at least Swift 5
• I used correctly sized dash and ended the entry with a full stop 🤓