fix: actually allow overriding remotes

[kylo252]

Description

ability to override the current branch's remote, which is useful for getting permalinks that use "origin", and not the temporary fork.

How to test

compare the results of these two functions before and after

require('gitlinker').get_buf_range_url('n', {remote = "origin"})
require('gitlinker').get_buf_range_url('n', {remote = "fork"})