Specify swift-tools-version

[martinK-7]

Currently, the Arkana swift package templates specify // swift-tools-version: 5.6, which is kinda outdated. In our project it leads to some issues, since due to Arkana SPM falls back to 5.6 even if we want to use 5.10.
We need some way to change this version, maybe this can be injected via the configuration file.

Thanks in advance!

Sources:
https://github.com/rogerluan/arkana/blob/main/lib/arkana/templates/swift/interfaces_package.swift.erb
https://github.com/rogerluan/arkana/blob/main/lib/arkana/templates/swift/package.swift.erb