Remove hash alias for unsafe_hash (#2454)

Author: debonte

pep-0681.rst

@@ -195,7 +195,6 @@ the bool value (``True`` or ``False``) to be statically evaluated.
 * ``eq``.  ``order``, ``frozen``, ``init`` and ``unsafe_hash`` are parameters
   supported in the stdlib dataclass, with meanings defined in 
   :pep:`PEP 557 <557#id7>`.
-* ``hash`` is an alias for the ``unsafe_hash`` parameter.
 * ``kw_only``, ``match_args`` and ``slots`` are parameters supported
   in the stdlib dataclass, first introduced in Python 3.10.