fix: datetime with timezone excel export (#25318)

Co-authored-by: Michael S. Molina <70410625+michael-s-molina@users.noreply.github.com>

tests/unit_tests/utils/excel_tests.py

@@ -0,0 +1,31 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# 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.
+
+from datetime import datetime, timezone
+
+import pandas as pd
+
+from superset.utils.excel import df_to_excel
+
+
+def test_timezone_conversion() -> None:
+    """
+    Test that columns with timezones are converted to a string.
+    """
+    df = pd.DataFrame({"dt": [datetime(2023, 1, 1, 0, 0, tzinfo=timezone.utc)]})
+    contents = df_to_excel(df)
+    assert pd.read_excel(contents)["dt"][0] == "2023-01-01 00:00:00+00:00"