Fix the GitHub defined terms for requests

[Kreyren]

Description

GitHub is using the term Pull Request for merge requests which makes no sense assuming that it implies to send a request to pull from something.

Proposing to use the term Merge Request

[techknowlogick]

This request has been made in the past and to reiterate we would prefer not to as we have routes and whatnot that use “pulls” and it would be a breaking change to switch to merge.

[Kreyren]

Transferred in https://codeberg.org/Codeberg/Community/issues/273 then