Update whatsnew and make it a separate test

Author: snitish

doc/source/whatsnew/v3.0.0.rst

@@ -789,6 +789,7 @@ Other
 - Bug in :meth:`Series.dt` methods in :class:`ArrowDtype` that were returning incorrect values. (:issue:`57355`)
 - Bug in :meth:`Series.rank` that doesn't preserve missing values for nullable integers when ``na_option='keep'``. (:issue:`56976`)
 - Bug in :meth:`Series.replace` and :meth:`DataFrame.replace` inconsistently replacing matching instances when ``regex=True`` and missing values are present. (:issue:`56599`)
+- Bug in :meth:`Series.to_string` when series contains complex floats with exponents (:issue:`60405`)
 - Bug in :meth:`read_csv` where chained fsspec TAR file and ``compression="infer"`` fails with ``tarfile.ReadError`` (:issue:`60028`)
 - Bug in Dataframe Interchange Protocol implementation was returning incorrect results for data buffers' associated dtype, for string and datetime columns (:issue:`54781`)
 - Bug in ``Series.list`` methods not preserving the original :class:`Index`. (:issue:`58425`)

pandas/tests/io/formats/test_to_string.py

@@ -422,6 +422,7 @@ def test_to_string_complex_float_formatting(self):
             )
             assert result == expected
 
+    def test_to_string_complex_float_formatting_with_exponents(self):
         # GH #60393
         with option_context("display.precision", 6):
             df = DataFrame(