fix uninitialized struct member #10152

Python/symtable.c

@@ -66,6 +66,7 @@ ste_new(struct symtable *st, identifier name, _Py_block_ty block,
     ste->ste_varkeywords = 0;
     ste->ste_opt_lineno = 0;
     ste->ste_opt_col_offset = 0;
+    ste->ste_tmpname = 0;
     ste->ste_lineno = lineno;
     ste->ste_col_offset = col_offset;