bpo-29673: fix gdb scripts pystack and pystackv (GH-6126)

diff --git a/Misc/ACKS b/Misc/ACKS
index f7ac37e..b951446 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1250,6 +1250,7 @@
 Antoine Pitrou
 Jean-François Piéronne
 Oleg Plakhotnyuk
+Marcel Plch
 Remi Pointel
 Jon Poler
 Ariel Poliak