Add GITHUB_TOKEN permissions for format job

[penelopeysm]

Closes #2293

(Edit: It partially fixes 2293, but not completely. See issue for more explanation.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.77%. Comparing base (b9f2cc0) to head (85ee241).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2294   +/-   ##
=======================================
  Coverage   85.77%   85.77%           
=======================================
  Files          24       24           
  Lines        1617     1617           
=======================================
  Hits         1387     1387           
  Misses        230      230           

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[yebai]

Thanks @penelopeysm!

[coveralls]

Pull Request Test Coverage Report for Build 10152567874

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 85.989%

---

Totals
Change from base Build 10151640416:	0.0%
Covered Lines:	1387
Relevant Lines:	1613

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💛 - Coveralls

[penelopeysm]

@yebai I just learnt that there is one more step for this. According to these GitHub docs, for PRs from public forks (such as #2290) the permissions are decreased to read-only unless the "Send write tokens to workflows from pull requests" option is selected in the repo settings.

You could either enable the setting, or if you trust me enough, make me an owner of the organisation and I can do it :)