chore: update dependency eslint to v7

Author: renovate-bot

package-lock.json

@@ -97,7 +97,7 @@
     "@babel/register": "7.9.0",
     "ava": "2.4.0",
     "babel-eslint": "10.1.0",
-    "eslint": "6.8.0",
+    "eslint": "7.0.0",
     "eslint-config-prettier": "6.11.0",
     "eslint-plugin-prettier": "3.1.3",
     "flow-bin": "0.124.0",