Support for `pyo3 = "^0.22.0"`

[SnowCheetos]

The current release for rust-numpy (v0.21.0) does not support the latest pyo3 version.

$ cargo add numpy

    Updating crates.io index
      Adding numpy v0.21.0 to dependencies
             Features:
             - half
             - nalgebra
    Updating crates.io index
error: failed to select a version for pyo3-ffi.
    ... required by package pyo3 v0.21.0
    ... which satisfies dependency pyo3 = "^0.21.0" of package numpy v0.21.0
    ... which satisfies dependency numpy = "^0.21.0" of package moonrs v0.1.0 (/home/cass/Documents/.S/AutoMoonBot/automoonbot/moonrs)
versions that meet the requirements =0.21.0 are: 0.21.0

the package pyo3-ffi links to the native library python, but it conflicts with a previous package which links to python as well:
package pyo3-ffi v0.22.2
    ... which satisfies dependency pyo3-ffi = "=0.22.2" of package pyo3 v0.22.2
    ... which satisfies dependency pyo3 = "^0.22.2" of package moonrs v0.1.0 (/home/cass/Documents/.S/AutoMoonBot/automoonbot/moonrs)
Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the links = "python" value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.

failed to select a version for pyo3-ffi which could resolve this conflict

[davidhewitt]

See #435

[ngoldbaum]

#435 is merged so I think this can be closed now.