fix(deps): upgrade ESLint to 7 to get no-void allowAsStatement

Author: jrolfs

package.json

@@ -84,7 +84,7 @@
     "cross-env": "^7.0.0",
     "cross-spawn": "^7.0.1",
     "doctoc": "^1.4.0",
-    "eslint": "^6.8.0",
+    "eslint": "^7.10.0",
     "eslint-config-airbnb-typescript": "^11.0.0",
     "eslint-config-kentcdodds": "^15.0.0",
     "eslint-config-prettier": "^6.12.0",