`np.float_` will be hard error in NumPy 2.0

[zm711]

Hey Alessio,

There's one more hard error coming in NumPy 2.0 where np.float_ will no longer be allowed. I didn't want to touch it in this function

MEArec/src/MEArec/tools.py

Line 769 in c2f394a

if isinstance(v, np.float_):

because you might need to jump through some hoops to keep backward compatibility along with forward compatibility, but just wanted to put it on your radar.