ci: improve GitHub Actions and Codecov Setup

- Update GitHub Actions cache step to use version 4
- Update Codecov GitHub Action to version 4

Signed-off-by: appleboy <appleboy.tw@gmail.com>

.github/workflows/go.yml

@@ -48,7 +48,7 @@ jobs:
         with:
           ref: ${{ github.ref }}
 
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: |
             ${{ matrix.go-build }}
@@ -61,6 +61,6 @@ jobs:
           go test -v -covermode=atomic -coverprofile=coverage.out
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           flags: ${{ matrix.os }},go-${{ matrix.go }}