v0.6.1

Fixes

• Fix an issue where define_clonotype failed when the clonotype network had no edges (#236).
• Require pandas >= 1.0 and fix a pandas incompatibility in merge_with_ir (#238).
• Ensure consistent order of the spectratype dataframe (#238).

Minor changes

• Fix missing bibtex_bibfiles option in sphinx configuration
• Work around pypa/flit#383.