Upgrade pyo3 to 0.16 (#956)

* Upgrade pyo3 to 0.15

Rebase-conflicts-fixed-by: H. Vetinari <h.vetinari@gmx.com>

* Upgrade pyo3 to 0.16

Rebase-conflicts-fixed-by: H. Vetinari <h.vetinari@gmx.com>

* Install Python before running cargo clippy

* Fix clippy warnings

* Use `PyArray_Check` instead of downcasting to `PyArray1<u8>`

* Enable `auto-initialize` of pyo3 to fix `cargo test
--no-default-features`

* Fix some test cases

Why do they change?

* Refactor and add SAFETY comments to `PyArrayUnicode`

Replace deprecated `PyUnicode_FromUnicode` with `PyUnicode_FromKindAndData`

Co-authored-by: messense <messense@icloud.com>

bindings/python/src/utils/iterators.rs

@@ -1,5 +1,5 @@
 use pyo3::prelude::*;
-use pyo3::{AsPyPointer, PyNativeType};
+use pyo3::AsPyPointer;
 use std::collections::VecDeque;
 
 /// An simple iterator that can be instantiated with a specified length.