ci: comment out gdk-pixbuf build for now

There appears to be an upstream issue with this package that should not block melange CI: https://gitlab.gnome.org/GNOME/gobject-introspection/-/issues/515

Also, it looks like this has happened before, see melange PR #1143 that was later reverted in PR #1147.

Signed-off-by: Dan Luhring <dluhring@chainguard.dev>

.github/workflows/wolfi-presubmit.yaml

@@ -63,7 +63,7 @@ jobs:
           - tini
           - lzo
           - bubblewrap
-          - gdk-pixbuf
+#          - gdk-pixbuf # Looks like this is broken again, see: https://gitlab.gnome.org/GNOME/gobject-introspection/-/issues/515
           - gitsign
           - guac
           - mdbook