Release v0.12.1-beta-Maintenance

[saubyk]

Maintenance release with minor updates and bug fixes following up on the last major release:
https://github.com/Ride-The-Lightning/RTL/releases/tag/v0.12.1

Change highlights:

• Bug fix for the BOLT12 QR code on the pdf export
• Usability improvements on the tool tips throughout the application
• Other bug fixes

Details of the changes here

Release contributors:
@ShahanaFarooqui @saiy2k