Upgrade to PyO3 0.22 (#203)

* Remove useless bounds on GroupFunc

* Use the new Bound<T> API

* Refresh tuto

* Use pyo3 0.22

* Use pyclass(eq, eq_int) and derive PartialEq

* Use pyo3(signature=...)

* Pin ndarray:0.15

* Finally commit Cargo.lock to pin ndarray 0.15

.gitignore

@@ -2,9 +2,8 @@
 # will have compiled files and executables
 **/target/
 
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
-# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
-Cargo.lock
+# See https://blog.rust-lang.org/2023/08/29/committing-lockfiles.html
+# Cargo.lock
 
 # These are backup files generated by rustfmt
 **/*.rs.bk