Support Swift Package Manager

[kiroskirin]

Is it possible that you make this library to support Swift Package Manager?

[4taras4]

Added SPM

[kiroskirin]

There is an error when I try to use this lib

.package(url: "https://github.com/4taras4/RSASwiftGenerator", .upToNextMajor(from: "1.0.0"))

OR

.package(url: "https://github.com/4taras4/RSASwiftGenerator", .exact("1.0.5"))

The package dependency graph can not be resolved; unable find any available tag for the following requirements:

https://github.com/4taras4/RSASwiftGenerator — 1.0.0..<2.0.0