about: add get_os_branch api call
Return TOS release branch or version (e.g. 4.0-beta11) through about-module.
related MR: turris/foris/foris!23 (merged)
Return TOS release branch or version (e.g. 4.0-beta11) through about-module.
related MR: turris/foris/foris!23 (merged)