Pep517 is now pyproject-hooks

The pep517 package on PyPI has been renamed to pyproject-hooks.

Along with this rename, the functionality that had equivalents in build has been removed from this package. And, as the name suggests, the project is now meant to provide a shared implementation of calling code for pyproject.toml-based build backend hooks.

For those curious about the specifics around the rename:

Thanks to @pradyunsg for doing lots of the work around this rename - including writing this announcement. :smiley: