chore(deps): update linters (#60)

Author: renovate-bot

package.json

@@ -28,8 +28,8 @@
   },
   "devDependencies": {
     "c8": "^5.0.1",
-    "eslint": "^5.16.0",
-    "eslint-config-prettier": "^4.2.0",
+    "eslint": "^6.0.0",
+    "eslint-config-prettier": "^6.0.0",
     "eslint-plugin-node": "^9.0.1",
     "eslint-plugin-prettier": "^3.1.0",
     "jsdoc": "^3.6.2",