ci: Bump Emacs 29.x to 4

Author: jcs090218

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
           - "26.3"
           - "27.2"
           - "28.2"
-          - "29.2"
+          - "29.4"
         experimental: [false]
         include:
           - os: ubuntu-latest