Constriction

Fixes signatures in python wheels, see 43.

Actually reduces the minimum required numpy version from 1.19 to 1.16.

The previous release already attempted to do this, but there was a mistake, see discussion in issue 40.

Reduces the minimum required numpy version from 1.19 to 1.16, as discussed in issue 40.

Add support for python 3.12

Allow 32-bit floating point representations for probabilities in the python API. This considerably simplifies prototyping.

The Rust API still uses 64 bit floating point precision since (i) internal calculations in the `probability` crate are done on `f64`s anyway, and (ii) the Rust API mostly favors iterators over vectors, so conversion to `f64` does not require any copying.

Update rust dependency on `probability` to version 0.20, which now supports `no_std`. This is a breaking change since `constriction` exposes traits from `probability` through its public API.

We also now verify `no_std` compatibility in all CI workflows.