Add changelog entry for PyO3#1200

Author: messense

Changelog.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+* **Breaking Change**: Remove support for specifying python package metadata in `Cargo.toml` in [#1200](https://github.com/PyO3/maturin/pull/1200).
+  Python package metadata should be specified in the `project` section of `pyproject.toml` instead as [PEP 621](https://peps.python.org/pep-0621/) specifies.
 * Initial support for shipping bin targets as wasm32-wasi binaries that are run through wasmtime in [#1107](https://github.com/PyO3/maturin/pull/1107). 
   Note that wasmtime currently only support the five most popular platforms and that wasi binaries have restrictions when interacting with the host.
   Usage is by setting `--target wasm32-wasi`.