Browserslist DB bump script using wrong branch

[doamatto]

What's the issue? Describe the problem below.
#211 shows commits from #171 being proposed for merge.

What did you expect to be the case instead?
The action (.github/workflows/browserslist.yml) should checkout master and bump the database there.

When it's applied to a MR, it should checkout that MR and merge into that MR. A good solution could be simply specifying that only master, like so :

on:
  push:
    branches:
      - main

Screenshots?
N/A

Additional context?
N/A