v0.2.0

Added

• Add --valid-for argument to xqr encode to set how long the token is valid for
  • When not set, the XQR will be valid forever
• Add --iss argument and pass to xqr encode to set the issuer

Changed

• Upgrade xqr to 0.4.0 (breaking changes)

Removed

• Remove --kid argument from xqr encode
  • The key id is now generated from the key