Ractor compatibility

[orlando-labs]

Hi.
First of all, thanks for Numo.

I propose to make numo ractor-safe in order to use it with ruby 3 ractors by calling rb_ractor_safe(true) in the C-code. Otherwise it is not possible to parallelise computational-expensive applications using Numo within newly introduced ractors.

Thanks

[kojix2]

If you could review this, it would be a contribution...
#199

[orlando-labs]

Thanks! I will try it with my current project and get back with the feedback, ok?

[orlando-labs]

#199 (comment)