fix linter

tests/core/data/test_write_single_sheet_excel_data_node.py

@@ -8,7 +8,6 @@
 # Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 # an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 # specific language governing permissions and limitations under the License.
-import contextlib
 import dataclasses
 import os
 import pathlib