Merge tag 'v0.51' of https://github.com/mail-in-a-box/mailinabox

v0.51 (November 14, 2020)

Software updates:

* Upgraded Nextcloud from 17.0.6 to 20.0.1 (with Contacts from 3.3.0 to 3.4.1 and Calendar from 2.0.3 to 2.1.2)
* Upgraded Roundcube to version 1.4.9.

Mail:

* The MTA-STA max_age value was increased to the normal one week.

Control Panel:

* Two-factor authentication can now be enabled for logins to the control panel. However, keep in mind that many online services (including domain name registrars, cloud server providers, and TLS certificate providers) may allow an attacker to take over your account or issue a fraudulent TLS certificate with only access to your email address, and this new two-factor authentication does not protect access to your inbox. It therefore remains very important that user accounts with administrative email addresses have strong passwords.
* TLS certificate expiry dates are now shown in ISO8601 format for clarity.

# gpg verification failed.

# Conflicts:
#	management/daemon.py
#	setup/bootstrap.sh
#	setup/mail-users.sh
#	tools/mail.py

management/mailconfig.py

@@ -720,7 +720,6 @@ def validate_password(pw):
 	if len(pw) < 8:
 		raise ValueError("Passwords must be at least eight characters.")
 
-
 if __name__ == "__main__":
 	import sys
 	if len(sys.argv) > 2 and sys.argv[1] == "validate-email":