CompatHelper: bump compat for "SpecialFunctions" to "2"

[github-actions]

This pull request changes the compat entry for the SpecialFunctions package from 1 to 1, 2.

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

Merging #80 (64332d5) into master (a3db592) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #80   +/-   ##
=======================================
  Coverage   90.78%   90.78%           
=======================================
  Files           4        4           
  Lines         282      282           
=======================================
  Hits          256      256           
  Misses         26       26           

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[theogf]

Only factorial was changed and we don't use it