CompatHelper: bump compat for "SpecialFunctions" to "0.9"

[github-actions]

This pull request changes the compat entry for the SpecialFunctions package from 0.8 to 0.8, 0.9.

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

@@           Coverage Diff           @@
##           master      #93   +/-   ##
=======================================
  Coverage   80.75%   80.75%           
=======================================
  Files          12       12           
  Lines        1247     1247           
=======================================
  Hits         1007     1007           
  Misses        240      240

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