Recently CI fails in Node v10+ because the devDeps are outdated.
This PR makes CI green in Node v10/12/13 with minimal devDeps updates.
Also Node v6 and v9 (EOL) are dropped from CI.
Further package-lock.json is updated and it resolves some security issues and closes the PRs.
Recently CI fails in Node v10+ because the devDeps are outdated. This PR makes CI green in Node v10/12/13 with minimal devDeps updates. Also Node v6 and v9 (EOL) are dropped from CI. Further package-lock.json is updated and it resolves some security issues and closes the PRs.