Refactor: add error handling for unknown channel type

See merge request !47

With the new liquidsoap versions all sources have a unique id, this id is used to create the namespace for the corresponding telnet commands. Since we alter the sources in liquidsoap multiple times we have a miss match in the namespace of some telnet commands. `mixer.inputs` returns a list of sources which may contain a id. This id is concatenated with the name of the source. For example `in_stream_0.1` is a valid response from `mixer.inputs`.  We therefore drop everything after the first `.`.

Improve test coverage: add DotDict initializer test

See merge request !45

make release: use poetry to avoid tomli import error

See merge request !44

Fix retry connect stream

See merge request !40

Rename ResourceType.PLAYLIST to .M3U

See merge request !43

Improve test coverage for `lang`

See merge request !42

Change `aura` UID:GID to value in the sysuser range

See merge request !41