9.0.0

Removed: Python 3.7 support
Removed: MappingMortar and MortarFacetBasis in favor of skfem.supermeshing
Deprecated: skfem.visuals.glvis; current version is broken and no replacement is being planned
Added: Python 3.12 support
Added: Mesh.load supports new keyword arguments ignore_orientation=True and ignore_interior_facets=True which will both speed up the loading of larger three-dimensional meshes by ignoring facet orientation and all tags not on the boundary, respectively.
Added: skfem.supermeshing (requires shapely>=2) for creating quadrature rules for interpolating between two 1D or 2D meshes.
Added: Mesh.remove_unused_nodes
Added: Mesh.remove_duplicate_nodes
Added: Mesh.remove_elements now supports passing any subdomain reference through Mesh.normalize_elements; subdomains and boundaries are also properly preserved
Fixed: MeshTet uniform refine was reindexing subdomains incorrectly
Fixed: MeshDG.draw did not work; now calls Basis.draw which works for any mesh topology
Fixed: FacetBasis now works with MeshTri2, MeshQuad2, MeshTet2 and MeshHex2
Fixed: ElementGlobal now uses outward normals to initialize DOFs on boundary facets