Remove xfail for test_chunk due to Xarray #9326 round() fix

Author: tomwhite

cubed_xarray/tests/test_xarray.py

@@ -148,7 +148,7 @@ def test_unary_op(self):
         v = self.lazy_var
         self.assertLazyAndIdentical(-u, -v)
         self.assertLazyAndIdentical(abs(u), abs(v))
-        # self.assertLazyAndIdentical(u.round(), v.round())  # TODO: fails, see https://github.com/pydata/xarray/pull/9326
+        self.assertLazyAndIdentical(u.round(), v.round())
 
     def test_binary_op(self):
         u = self.eager_var