Update the config api

[SnarkBoojum]

The api used by recent minetest versions is different.

The following patch fixes the warnings.
update_config_api.txt

I hope that helps.

[sofar]

FIxed in github.com/minetest-mods/nether 57b2d30

[SnarkBoojum]

Could you tag a new release and close that issue? Thanks!