[oauth] update scope for reddit tokens (#428)

'/user/<username>/...' requires the 'history' scope to be accessible
(https://www.reddit.com/dev/api/#GET_user_{username}_{where})

gallery_dl/extractor/oauth.py

@@ -213,7 +213,7 @@ def items(self):
             "",
             "https://www.reddit.com/api/v1/authorize",
             "https://www.reddit.com/api/v1/access_token",
-            scope="read",
+            scope="read history",
         )