[Snyk] Security upgrade mocha from 1.21.5 to 6.2.3#6

snyk-bot wants to merge 1 commit intomasterMailOnline/grunt-css-annotator:masterfrom

snyk-fix-7ef7ce88e348574b90d353ad962783c5MailOnline/grunt-css-annotator:snyk-fix-7ef7ce88e348574b90d353ad962783c5Copy head branch name to clipboard