PEP 751: Fix typo in dependency_groups (#4339)

Author: savannahostrowski

peps/pep-0751.rst

@@ -805,7 +805,7 @@ operations involving sets:
       python_version ~= "surprise"
 
 
-Fourth, use of ``extras`` and ``depenendency_groups`` will be considered an
+Fourth, use of ``extras`` and ``dependency_groups`` will be considered an
 error outside of lock file (much like ``extra`` outside of
 :ref:`packaging:core-metadata`).