ci: Bump Emacs 29.x to 3

Author: jcs090218

.github/workflows/main.yml

@@ -23,7 +23,7 @@ jobs:
           - 26.3
           - 27.2
           - 28.2
-          - 29.2
+          - 29.3
         experimental: [false]
         include:
           - os: ubuntu-latest