Update main.yml

Author: xdager

.github/workflows/main.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           ref: develop
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
           path: ~/.cache
           key: ${{ runner.os }}-gem-${{ hashFiles('**/Gemfile.lock') }}