bpo-36811: Fix a C compiler warning in _elementtree.c. (GH-13109)

Modules/_elementtree.c

@@ -1171,7 +1171,7 @@ checkpath(PyObject* tag)
         char *p = PyBytes_AS_STRING(tag);
         const Py_ssize_t len = PyBytes_GET_SIZE(tag);
         if (len >= 3 && p[0] == '{' && (
-                p[1] == '}' || p[1] == '*' && p[2] == '}')) {
+                p[1] == '}' || (p[1] == '*' && p[2] == '}'))) {
             /* wildcard: '{}tag' or '{*}tag' */
             return 1;
         }