bpo-40750: Support -d flag in the new parser (GH-20340)

(cherry picked from commit 800a35c623bbcdb5793c7d7a4974524286311479)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
diff --git a/Parser/pegen/pegen.c b/Parser/pegen/pegen.c
index 9cade2a..cd87a9f 100644
--- a/Parser/pegen/pegen.c
+++ b/Parser/pegen/pegen.c
@@ -1027,6 +1027,7 @@
     p->flags = flags;
     p->feature_version = feature_version;
     p->known_err_token = NULL;
+    p->level = 0;
 
     return p;
 }