antora: update software versions ✨

Triggered by update-versions GitHub Action.

Author: coreosbot

antora.yml

@@ -10,6 +10,6 @@ asciidoc:
   attributes:
     stable-version: 44.20260607.3.1
     ignition-version: 2.26.0
-    butane-version: 0.28.0
+    butane-version: 0.29.0
     butane-latest-stable-spec: 1.7.0
     ignition-latest-stable-spec: 3.6.0