Make axolotls faster

The newly added axolotls (20w51a) are meant to be an aid in combat, allowing players to create an underwater army.

There is a problem, though. They can't keep up with you. Players wearing Depth Strider II - III boots will find out that their axolotls stop following them, as they are left behind (They are not pets, after all. They just follow you around because you are holding their favorite fish).

Making axolotls faster (with varying speeds, even), will let players go on adventures underwater, without having to stop every now and then just to check if their army is still there.