ci: upgrade actions

- Bump actions/checkout to v4
- Bump actions/cache to v4

Author: muzimuzhi

.github/workflows/main.yml

@@ -11,12 +11,12 @@ jobs:
         engine: [lualatex]
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       with:
         fetch-depth: 0
 
     - name: Cache dependencies
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: |
           /tmp/texlive