Bump flat and mocha in /src/chapter-listings#51

dependabot[bot] wants to merge 1 commit intomasterJoyOfJavaScript/joj:masterfrom

dependabot/npm_and_yarn/src/chapter-listings/flat-and-mocha-5.0.2JoyOfJavaScript/joj:dependabot/npm_and_yarn/src/chapter-listings/flat-and-mocha-5.0.2Copy head branch name to clipboard