fix: moment format strings -> date-fns format strings (#1568)
fix: moment format strings -> date-fns format strings (#1568)

Co-authored-by: Theodore Kluge <61559b134d538e079f48f9933773c8aaada2caef@fmm.com>
jquense/react-big-calendar,TeaBough/react-big-calendar,jquense/react-big-calendar,jquense/react-big-calendar