ci: Upgrade to actions/[email protected] because the old versions no longer work

Author: Maverobot

.github/workflows/main.yml

@@ -23,7 +23,7 @@ jobs:
         uses: actions/checkout@v3
 
       - name: Cache the spacemacs repository folder
-        uses: actions/cache@v3.3.2
+        uses: actions/cache@v4.0.0
         with:
           path: ~/.emacs.d
           key: saved-emacs-d-${{ matrix.os }}