PyO3 Python tests

These crates are a collection of test extension modules built with PyO3. They are all tested using tox in PyO3's CI.

Below is a brief description of each of these:

Example	Description
`pyo3-benchmarks`	A project containing some benchmarks of PyO3 functionality called from Python.
`pyo3-pytests`	A project containing some tests of PyO3 functionality called from Python.