bump cache action

Author: mjudeikis

.github/workflows/gh-pages.yml

@@ -37,7 +37,7 @@ jobs:
         with:
           node-version: "16"
       - name: Cache dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.npm
           key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}