Bump acorn from 6.1.1 to 6.4.1#22

hdgarrood merged 1 commit intomasterpurescript-contrib/purescript-js-date:masterfrom

dependabot/npm_and_yarn/acorn-6.4.1purescript-contrib/purescript-js-date:dependabot/npm_and_yarn/acorn-6.4.1Copy head branch name to clipboard