v1.23

Mos tool:

• Fix brew build: mos shouldn't check for updates because when installed via
  brew it should be updated also via brew

Firmware:

• BREAKING: SNTP is now factored out to a separate library, so apps should include it explicitly if that functionality is needed.
• Implemented mgos_event_add_group_handler() in C and
  Event.addGroupHandler() in mJS
• BREAKING: mgos_net_add_event_handler() is deprecated in favor of mgos_event-based
  API. See comment for MGOS_EVENT_GRP_NET for the example.
• Increased CC32xx UART buffer size
• Many improvements in dashboard support (and in the dashboard itself)
• Added DigiCert root