Update doc/source/whatsnew/v3.0.0.rst

Removing unit test from what's new

Co-authored-by: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>

Author: vijmeister

doc/source/whatsnew/v3.0.0.rst

@@ -979,7 +979,6 @@ Timedelta
 ^^^^^^^^^
 - Accuracy improvement in :meth:`Timedelta.to_pytimedelta` to round microseconds consistently for large nanosecond based Timedelta (:issue:`57841`)
 - Bug in :class:`Timedelta` constructor failing to raise when passed an invalid keyword (:issue:`53801`)
-- Bug in :class:`Timedelta` constructor failing to recognize Week ('W') as a parsed string suffix (:issue:`12691`)
 - Bug in :meth:`DataFrame.cumsum` which was raising ``IndexError`` if dtype is ``timedelta64[ns]`` (:issue:`57956`)
 - Bug in multiplication operations with ``timedelta64`` dtype failing to raise ``TypeError`` when multiplying by ``bool`` objects or dtypes (:issue:`58054`)