Install poetry via pipx rather than curl
This addresses #724 (closed) by installing poetry
via pipx
rather than piping the output of curl
into a shell.
pipx installs poetry into an isolated environment, and in doing so will not mix in poetry with gwcelery and its dependencies in a single environment as it appears what is being done currently.
Supercedes !1357 (closed).
Closes #724 (closed).
Edited by Patrick Godwin