1.4.0

What's Changed

• Remove requirements-archive by @Joseph-Edwards in #383
• transf: future proof __getitem__ by @james-d-mitchell in #382
• todd-coxeter: update for changes in libsemigroups by @james-d-mitchell in #388
• transf: don't allow mult. when degrees differ by @james-d-mitchell in #394
• Sims: check that Sims1/2 is initialised before add SimsRefinerIdeals by @james-d-mitchell in #396

Full Changelog: v1.3.0...v1.4.0