chore(deps): update linters (#274)

Author: renovate-bot

packages/google-cloud-language/package.json

@@ -46,8 +46,8 @@
   },
   "devDependencies": {
     "codecov": "^3.0.2",
-    "eslint": "^5.0.0",
-    "eslint-config-prettier": "^4.0.0",
+    "eslint": "^6.0.0",
+    "eslint-config-prettier": "^6.0.0",
     "eslint-plugin-node": "^9.0.0",
     "eslint-plugin-prettier": "^3.0.0",
     "jsdoc-baseline": "^0.1.0",