This Adafruit_HX8357 library is my port that I haven't yet migrated to Libraries v2.0
I'll do it ASAP an report back when done.
Thanks for the heads-up
Meanwhile you could try a previous version of the Adafruit_mfGFX library that wasn't yet migrated to v2.0.
You can do that by clicking on the (i) icon next to the library name and then clicking on the previous version number.
Update:
I've got the fix, but currently have problems uploading the new release due to some unexpected issue