[Snyk] Security upgrade html-proofer from 3.19.1 to 3.19.3#1

CalinL wants to merge 1 commit intomaingithubabcs/caption-this:mainfrom

snyk-fix-524571ee91f89f4ab1beca1583c17acagithubabcs/caption-this:snyk-fix-524571ee91f89f4ab1beca1583c17acaCopy head branch name to clipboard