v6.9.1

This is the first installable 6.9.x release. The v6.9.0 package was missing a data file it
reads at runtime, so it could not be imported after installation; everything v6.9.0 announced
arrives here. Its notes are the changelog for this release too:
v6.9.0 release notes.

Fixes

• Installed packages were unusable. transformers/lib_types.json and transformers/edge_rules.json are read at runtime from the package directory, but neither MANIFEST.in nor the package-data globs covered them, so they never reached the built wheel or sdist. Every import pynecore from an installed package raised FileNotFoundError on lib_types.json. Both files now ship with the distribution.

There are no functional changes beyond the packaging fix; the code is otherwise identical to v6.9.0.