Bump version for 2.4.0
Bump version for 2.4.0

dnephin/jsonschema,eodolphi/jsonschema,jamesmarva/jsonschema,varunarya10/jsonschema,python-jsonschema/jsonschema,Julian/jsonschema,sightmachine/jsonschema,eodolphi/jsonschema,Julian/jsonschema,mathewmarcus/jsonschema