CompatHelper: bump compat for Documenter to 1 for package test, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the Documenter package from 0.25, 0.26, 0.27 to 0.25, 0.26, 0.27, 1 for package test.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.88%. Comparing base (2a6e5e9) to head (7e9f40b).
Report is 12 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #524   +/-   ##
=======================================
  Coverage   90.88%   90.88%           
=======================================
  Files          52       52           
  Lines        1459     1459           
=======================================
  Hits         1326     1326           
  Misses        133      133           

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