Fix poetry config not taking effect inside GitHub Actions  (#1241)
Fix poetry config not taking effect inside GitHub Actions  (#1241)

poetry stores its config in `$HOME/config/pypoetry/config.toml`.
At build time, `$HOME` is `/root`. When run inside GitHub Actions,
`$HOME` is set to `/github/home` and poetry loses its config.
Use environment variables to set the poetry config instead.
matrix-org/sytest,matrix-org/sytest