Translations are not enabled when using polyglossia

[viccie30]

apa7.cls specifically checks if babel is loaded, but does not consider polyglossia: https://github.com/dan-weiss/apa7-latex-cls-source/blob/62f31e0b2c8c75e260a7690928c745d803333549/apa7/apa7.dtx#L1498-L1504

I think either polyglossia should also be checked for or something like tracklang should be used to detect the current language.

[dan-weiss]

I haven't used those packages before but I'm happy to review a pull request if you know how to integrate those packages.

[viccie30]

I will give it a try and open a pull request.