Add support for "polutonikogreek"

[koppor]

I get

 pg 27: Package csquotes Warning: No style for language 'polutonikogreek'.
       (csquotes)                Using fallback style on input line 25.

(At the CI check https://github.com/thomas-hilarius-meyer/LaTeX-fuer-Geisteswissenschaftler/actions/runs/8660150572/job/23747547751?pr=147)

Think, I should report that.

@thomas-hilarius-meyer Do you have an idea about the right quote signs?