Log Message:
py-pyproject_hooks: update to 1.2.0.

v1.2
----

- Improve interoperability with ``importlib.metadata``, fixing a regression
  in setuptools compatibility in 1.1 (#199).
- Clean up the ``_in_process`` directory inside the package from ``sys.path``
  before imporing the backend (#193).

v1.1
----

- Add type annotations to the public API.
- More careful handling of the ``backend-path`` key from ``pyproject.toml``.
  Previous versions would load the backend and then check that it was loaded
  from the specified path; the new version only loads it from the specified path.
  The ``BackendInvalid`` exception is now a synonym for :exc:`BackendUnavailable`,
  and code should move to using the latter name.