修改pods

Pods/FirebaseFirestore/Firestore/Swift/Source/Codable/EncoderDecoder.swift

@@ -93,7 +93,7 @@ public extension Firestore {
 
     public func decode<T: Decodable>(_ t: T.Type, from data: Any,
                                      in reference: DocumentReference?) throws -> T {
-      if let reference = reference {
+      if let reference {
         userInfo[CodingUserInfoKey.documentRefUserInfoKey] = reference
       }
       return try decode(T.self, from: data)