[Snyk] Upgrade async from 2.6.0 to 2.6.3#2

snyk-bot wants to merge 1 commit intomastercontentascode/metalsmith-remark-lint:masterfrom

snyk-upgrade-30e69e40aabf26cc522f0cd69c964f27contentascode/metalsmith-remark-lint:snyk-upgrade-30e69e40aabf26cc522f0cd69c964f27Copy head branch name to clipboard