CompatHelper: bump compat for StatsBase to 0.34, (keep existing compat)

[github-actions[bot]]

This pull request changes the compat entry for the StatsBase package from 0.29, 0.30, 0.31, 0.32, 0.33 to 0.29, 0.30, 0.31, 0.32, 0.33, 0.34. 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.

[ablaom]

Be great if this could get some attention. This is holding up downstream packages; see e.g. linked issue below.

[ablaom]

@pkofod

[pkofod]

done, sorry

[ablaom]

Thank you!