[master] 63d6f3f2b vtest2: Plug empty h2 header value leak

[Dridi Boukelmoune]

commit 63d6f3f2b56658b09df1a39c6498722ac30e100d
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Tue Jun 24 09:22:24 2025 +0200

    vtest2: Plug empty h2 header value leak

diff --git a/bin/varnishtest/vtest2 b/bin/varnishtest/vtest2
index 6a62e4b28..4cffb5a3c 160000
--- a/bin/varnishtest/vtest2
+++ b/bin/varnishtest/vtest2
@@ -1 +1 @@
-Subproject commit 6a62e4b2823b3751e4eda805bf9990376437d8b5
+Subproject commit 4cffb5a3c49e270305c20fc9824a213193ef26af