Closes #6139: Removes bors

[sblatz]

I'm sorry, Dave, I'm afraid I can't do that.

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Pull Request checklist

• Tests: This PR includes thorough tests or an explanation of why it does not
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features

After merge

• Milestone: Make sure issues finished by this pull request are added to the milestone of the version currently in development.

To download an APK when reviewing a PR:

1. click on Show All Checks,
2. click Details next to "Taskcluster (pull_request)" after it appears and then finishes with a green checkmark,
3. click on the "Fenix - assemble" task, then click "Run Artifacts".
4. the APK links should be on the left side of the screen, named for each CPU architecture

[codecov-io]

Codecov Report

Merging #7247 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #7247   +/-   ##
=========================================
  Coverage     18.93%   18.93%           
  Complexity      436      436           
=========================================
  Files           289      289           
  Lines         11298    11298           
  Branches       1542     1542           
=========================================
  Hits           2139     2139           
  Misses         8995     8995           
  Partials        164      164

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[JohanLorenzo]

👍

To future readers: please see #6139 (comment) to understand why I'm okay to remove bors from Fenix.