Electrum 4.0.7 Release

December 9, 2020

Kivy improvements:
- Resolved issue with opening channels using max amount
- Corrected regression from previous version (a9fc440)
Various minor GUI enhancements
Dependency updates following dnspython adaptation (#6828):
- python-ecdsa removed from requirements
- cryptography now mandatory (version 2.6 minimum), replacing user choice between cryptography and pycryptodomex