fix: tools/node_modules/eslint/node_modules/gensync/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-AJV-584908
- https://snyk.io/vuln/SNYK-JS-ANSIREGEX-1583908
- https://snyk.io/vuln/SNYK-JS-MERGE-1040469
- https://snyk.io/vuln/SNYK-JS-MERGE-1042987
- https://snyk.io/vuln/SNYK-JS-SEMVER-3247795
- https://snyk.io/vuln/SNYK-JS-TOUGHCOOKIE-5672873
- https://snyk.io/vuln/SNYK-JS-YARGSPARSER-560381
- https://snyk.io/vuln/npm:braces:20180219
- https://snyk.io/vuln/npm:mem:20180117

Author: snyk-bot