bpo-30877: Fix clearing a cache in the the JSON decoder. (GH-7048)

(cherry picked from commit ae00fb1d4f38ea1803b10d798564740adcdad63e)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Lib/json/scanner.py b/Lib/json/scanner.py
index c451eba..7a61cfc 100644
--- a/Lib/json/scanner.py
+++ b/Lib/json/scanner.py
@@ -68,6 +68,6 @@
         finally:
             memo.clear()
 
-    return _scan_once
+    return scan_once
 
 make_scanner = c_make_scanner or py_make_scanner