Fix firestore plist (#163)

Added firebase-game-loop in Info.plist

Author: sunmou99

firestore/integration_test/Info.plist

@@ -26,6 +26,7 @@
 <key>CFBundleURLSchemes</key>
 <array>
 <string>REPLACE_WITH_REVERSED_CLIENT_ID</string>
+<string>firebase-game-loop</string>
 </array>
 </dict>
 </array>