upgrade cache v4

Author: foxundermoon

.github/workflows/CD.yml

@@ -50,7 +50,7 @@ jobs:
         id: yarn-cache-dir-path
         run: echo "::set-output name=dir::$(yarn cache dir)"
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: yarn-cache # use this to check for `cache-hit` (`steps.yarn-cache.outputs.cache-hit != 'true'`)
         with:
           path: ${{ steps.yarn-cache-dir-path.outputs.dir }}