Also use cache@v4 for matrix builds

Author: ricardoboss

.github/workflows/dart.yml

@@ -46,7 +46,7 @@ jobs:
         with:
           sdk: ${{ matrix.sdk }}
 
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: ${{ env.PUB_CACHE }}
           key: ${{ runner.os }}-pub-${{ matrix.sdk }}