Fix CI failures due to imports in test_complex.py

Author: micol-altomare

pandas/tests/io/pytables/test_complex.py

@@ -1,16 +1,17 @@
 import numpy as np
 import pytest
-import tables
-
 
 import pandas as pd
+import pandas._testing as tm
 from pandas import (
     DataFrame,
     HDFStore,
     Series,
     read_hdf,
 )
-import pandas._testing as tm
+
+
+tables = pytest.importorskip("tables")
 
 
 def test_complex_fixed(tmp_path, setup_path):