dolfin-convert is ridiculously old and has not been maintained for a long time.
See Using the GMSH Python API to generate complex meshes | Jørgen S. Dokken and/or Mesh generation and conversion with GMSH and PYGMSH | Jørgen S. Dokken. Also consider GitHub - nschloe/meshio: input/output for many mesh formats. Also the very lengthy and popular thread https://fenicsproject.discourse.group/t/transitioning-from-mesh-xml-to-mesh-xdmf-from-dolfin-convert-to-meshio.