Fix a refleak in _sre

Misc/NEWS

@@ -54,6 +54,8 @@ Core and Builtins
 Library
 -------
 
+- Fix a reference count leak in _sre.
+
 - Issue #19262: Initial check in of the 'asyncio' package (a.k.a. Tulip,
   a.k.a. PEP 3156).  There are no docs yet, and the PEP is slightly
   out of date with the code.  This module will have *provisional* status

Modules/_sre.c

@@ -2427,6 +2427,7 @@ next:
         else
             item = PyUnicode_Join(joiner, list);
         Py_DECREF(joiner);
+        Py_DECREF(list);
         if (!item)
             return NULL;
     }