CompatHelper: bump compat for FractionalCalculus to 0.2, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the FractionalCalculus package from 0.1.5 to 0.1.5, 0.2.
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-commenter]

Codecov Report

Merging #14 (0c0a829) into master (0f0afba) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #14   +/-   ##
=======================================
  Coverage   37.55%   37.55%           
=======================================
  Files           9        9           
  Lines         450      450           
=======================================
  Hits          169      169           
  Misses        281      281           

---

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 0f0afba...0c0a829. Read the comment docs.