Fix CI workflow: update deprecated actions to latest versions

Author: C0ldSmi1e

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
           go-version: '1.24'
 
       - name: Cache Go modules
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/go/pkg/mod
           key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
@@ -75,7 +75,7 @@ jobs:
           fi
 
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: dtree-${{ matrix.goos }}-${{ matrix.goarch }}
           path: dtree-*