update @google-cloud/firestore version

Author: 菊池健吾

package-lock.json

@@ -168,7 +168,7 @@
     "node-forge": "^1.0.0"
   },
   "optionalDependencies": {
-    "@google-cloud/firestore": "^4.5.0",
+    "@google-cloud/firestore": "^5.0.1",
     "@google-cloud/storage": "^5.3.0"
   },
   "devDependencies": {