[Proposal] Allow to specify dtype for Discrete

[younik]

Proposal

Add dtype argument to spaces.Discrete (similar to MultiDiscrete and Box).

Motivation

Currently the dtype is fixed to numpy.int64. However, often Discrete spaces are much smaller, resulting in a waste of memory.

Pitch

No response

Alternatives

No response

Additional context

No response

Checklist

• I have checked that there is no similar issue in the repo

[pseudo-rnd-thoughts]

Sure, if you can update all the functions and update the example testing spaces with dtypes

[JDRanpariya]

I would like to work on the issue.

Can you guide me on what other functions needs to be updated if we default it to int8 or int32 in constructor?

With example testing spaces do you mean tests/spaces/test_discrete.py? There is no explicit dtype checks in multidiscrete test, can you tell what needs to be done there?