Clean up uart gen server

nerves: update giraffe's fwup config

use github.workspace instead of env.GITHUB_WORKSPACE

fix get disk model and serial number

Release v0.20.0 (#665)

* upgrade version

* do not send error logs to sentry

* upgrade json logger dep

upgrade erlang in Dockerfile

Release v0.19.0 (#633)

* upgrade deps

* update version

* update readme

add env variables to nerves workflow

update nerves github action

fix conversion from annexb to elementary stream (#509)

* fix conversion from annexb to elementray stream

* update version