Time Series: Skip testing notebooks not compatible with pandas 2.x

- exploratory_data_analysis.ipynb
- time-series-decomposition.ipynb

They are not ready for pandas 2.x yet, and block others from being
upgraded. Apparently, Google Colab now strictly requires pandas 2.x?

topic/timeseries/test.py

@@ -19,5 +19,8 @@ def test_notebook(notebook):
             raise pytest.skip(f"Kaggle dataset can not be tested "
                               f"without authentication: {notebook.name}")
 
+    if notebook.name in ["exploratory_data_analysis.ipynb", "time-series-decomposition.ipynb"]:
+        raise pytest.skip(f"Notebook is not compatible with pandas 2.x: {notebook.name}")
+
     with testbook(notebook) as tb:
         tb.execute()