ci: install enchant in staging box
ci: install enchant in staging box

the choice here is to:

1. install enchant in the staging machine
2. break up development dependencies into what is needed for linting
and what is needed for the provisioning of staging machines

selecting the former, as having too many requirements files has
caused major confusion in the past.

conorsch/securedrop,conorsch/securedrop,conorsch/securedrop,conorsch/securedrop,conorsch/securedrop