chore(deps): update dependency eslint to v7.20.0

Author: renovate-bot

functions/package-lock.json

@@ -26,7 +26,7 @@
     "@types/nunjucks": "3.1.3",
     "@typescript-eslint/eslint-plugin": "3.10.1",
     "@typescript-eslint/parser": "3.10.1",
-    "eslint": "7.18.0",
+    "eslint": "7.20.0",
     "eslint-plugin-import": "2.22.1",
     "firebase-functions-test": "0.2.3",
     "typescript": "4.1.3"