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

[github-actions]

This pull request changes the compat entry for the SpecialFunctions package from 0.7.2 to 0.7.2, 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-io]

Codecov Report

Merging #40 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #40   +/-   ##
=======================================
  Coverage   99.43%   99.43%           
=======================================
  Files          12       12           
  Lines         882      882           
=======================================
  Hits          877      877           
  Misses          5        5

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 347e2aa...8fce9f8. Read the comment docs.