Upgrade mikeio to 3.1.0 and fix broken test

GeometryFM2D.is_2d was removed in mikeio 3.1.0; removed the obsolete assertion.

Author: ecomodeller

tests/model/test_dfsu.py

@@ -70,9 +70,6 @@ def test_dfsu_repr(hd_oresund_2d):
 def test_dfsu_properties(hd_oresund_2d):
     mr = ms.model_result(hd_oresund_2d, name="Oresund2d", item="Surface elevation")
 
-    # TODO Not sure this assert is useful
-    assert mr.data.geometry.is_2d
-
     # Note != name of item
     assert mr.quantity.name == "Surface Elevation"
     assert mr.quantity.unit == "m"