Switch to using poetry

[devonh]

This brings sygnal in line with synapse & allows the use of a poetry.lock file to track dependency versions more precisely.

[erikjohnston]

Thank you! This looks good, but I think we need to update the dockerfile to use poetry?

[devonh]

Thank you! This looks good, but I think we need to update the dockerfile to use poetry?

Ah! I knew I must be missing something. Will do.

[erikjohnston]

Otherwise looks good. I assume you've manually tested building and running the docker image?