temp/gtk+3.0: rework the version fix + temp/epiphany: version bump

This adresses https://gitlab.com/postmarketOS/pmaports/-/issues/841 by changing https://gitlab.com/postmarketOS/pmaports/-/merge_requests/1500:

GTK fix rework to return 3.90.99 instead of 3.99.99 + epiphany version bump.

I'm not sure if it breaks the fix (in theory it shouldn't since 3.90.99 is much newer than from Alpine) but could anyone take a look?