Setuptools-rust

- Fix `tomlgen` functionality on Windows. [78](https://github.com/PyO3/setuptools-rust/pull/78)
- Add support for building abi3 shared objects. [82](https://github.com/PyO3/setuptools-rust/pull/82)

- Fix building on Linux distributions that use musl (e.g. Alpine) out of the box. [80](https://github.com/PyO3/setuptools-rust/pull/80)

- Fix support for namespace packages. [79](https://github.com/PyO3/setuptools-rust/pull/79)

- Fix building for 32-bit Python on 64-bit Windows. [77](https://github.com/PyO3/setuptools-rust/pull/77)

- Remove python 2 support. [53](https://github.com/PyO3/setuptools-rust/pull/53)
- Fix compatibility with `cffi`. [68](https://github.com/PyO3/setuptools-rust/pull/68)
- Add support for pyo3 `0.12`'s `PYO3_PYTHON` setting. [71](https://github.com/PyO3/setuptools-rust/pull/71)

- Fix tomlgen\_rust generating invalid `Cargo.toml` files.
- Fix tomlgen\_rust setting wrong path in `.cargo/config`.