chore(deps-dev): bump standard from 14.3.4 to 15.0.0

Author: dependabot-preview[bot]

package.json

@@ -42,7 +42,7 @@
  "rxjs": "^6.5.3",
  "sinon": "^9.0.0",
  "source-map-loader": "^1.0.0",
- "standard": "^14.3.1",
+ "standard": "^15.0.0",
  "ts-jest": "^26.0.0",
  "ts-loader": "^8.0.0",
  "tslint": "^5.20.1",