DOC: Edited docstring of Interval (pandas-dev#25410)

The docstring contained a repeated segment, which I removed.

Author: wdecoster

pandas/_libs/interval.pyx

@@ -150,9 +150,6 @@ cdef class Interval(IntervalMixin):
         Left bound for the interval.
     right : orderable scalar
         Right bound for the interval.
-    closed : {'left', 'right', 'both', 'neither'}, default 'right'
-        Whether the interval is closed on the left-side, right-side, both or
-        neither.
     closed : {'right', 'left', 'both', 'neither'}, default 'right'
         Whether the interval is closed on the left-side, right-side, both or
         neither. See the Notes for more detailed explanation.