Remove note about development branch
When starting Kea daemons, a warning about dev version is printed:
CA prints [kea-ctrl-agent.dctl/16221.139754239903616] DCTL_DEVELOPMENT_VERSION This software is a development branch of Kea. It is not recommended for production use
It should be removed before 2.0.
DHCPv4 prints 2021-09-22 12:23:10.729 WARN [kea-dhcp4.dhcp4/16241.140525107655808] DHCP4_DEVELOPMENT_VERSION This software is a development branch of Kea. It is not recommended for production use.
Other daemons likely print similar messages. They should be removed before 2.0.