[twitter] fix issue when filtering quote tweets (#1792)

When a user quotes his own Tweet and that Tweet gets filtered by
'"quoted": false', it could also get filtered when it appeared later
as regular Tweet.

gallery_dl/extractor/twitter.py

@@ -882,6 +882,7 @@ class TwitterAPI():
                 if "quoted_status_id_str" in tweet:
                     quoted = tweets.get(tweet["quoted_status_id_str"])
                     if quoted:
+                        quoted = quoted.copy()
                         quoted["author"] = users[quoted["user_id_str"]]
                         quoted["user"] = tweet["user"]
                         quoted["quoted"] = True