v0.12.0

What's Changed

• bump sphinx and pydata-sphinx to more recent versions by @jcapriot in #402
• Small cleanups to the external TreeMesh code, no functionality changes by @jcapriot in #400
• Add point2index functionality for tensor_mesh by @jcapriot in #401
• Updates for python free threading by @jcapriot in #403
• Updates for cibuildwheel by @jcapriot in #405
• Add functionality to refine a TreeMesh using an "image" by @jcapriot in #406
• V0.12.0 staging by @jcapriot in #407

Full Changelog: v0.11.3...v0.12.0