Ci: Update actions/cache@v4

Author: TheOneRing

.github/workflows/main.yml

@@ -69,7 +69,7 @@ jobs:
         submodules: true
 
     - name: Restore cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: ~/cache
         key: ${{ runner.os }}-${{ matrix.target }}