Implement IntoPy<PyObject> for &PathBuf and &OsString

[messense]

Without this impl users need to call as_path() to convert a &PathBuf to a &Path, for example messense/rjsonnet-py@b29e161

Otherwise the error message is not easy to understand:

error[E0277]: the trait bound `PathBuf: AsPyPointer` is not satisfied
  --> src/lib.rs:34:55
   |
34 |             Python::with_gil(|py| match self.callback.call(py, (from, path), None) {
   |                                                       ^^^^ the trait `AsPyPointer` is not implemented for `PathBuf`
   |
   = note: required because of the requirements on the impl of `pyo3::IntoPy<Py<PyAny>>` for `&PathBuf`
   = note: 1 redundant requirements hidden
   = note: required because of the requirements on the impl of `pyo3::IntoPy<Py<PyTuple>>` for `(&PathBuf, &PathBuf)`

[davidhewitt]

👍 Can you add it for &OsString too please? That would then be consistent with &String, which already exists. Otherwise LGTM!

Btw I am preparing a 0.14.1 release today to fix a PyPy crash found in pyca/cryptography#6154, happy to see this PR merged and included in the release too.

[messense]

👍 Can you add it for &OsString too please? That would then be consistent with &String, which already exists.

Added.

[davidhewitt]

That's great, thanks!