[add]: eslint in package.json

Author: rahuldkjain

package.json

@@ -9,6 +9,7 @@
     "enzyme": "^3.11.0",
     "enzyme-adapter-react-16": "^1.15.5",
     "enzyme-to-json": "^3.6.1",
+    "eslint": "^7.17.0",
     "gatsby": "^2.23.12",
     "gatsby-image": "^2.4.9",
     "gatsby-plugin-google-analytics": "^2.3.11",