[ci] Upgrade Emacs 29.3 to 29.4

Author: bcc32

.github/workflows/elisp_test.yml

@@ -30,7 +30,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        emacs_version: [29.3, 30.1]
+        emacs_version: [29.4, 30.1]
     steps:
 # Installing Emacs on Unix
     - name: Install Emacs on UNIX