Fix actions/cache action deprecation

Author: ekzhang

.github/workflows/mean_bean_deploy.yml

@@ -54,7 +54,7 @@ jobs:
 
       # Cache files between builds
       - name: Setup | Cache Cargo
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: |
             ~/.cargo/registry