workaround for negative zero in doctests

Author: behackl

manim/mobject/geometry.py

@@ -932,7 +932,7 @@ def base(self):
         --------
         ::
             >>> arrow = Arrow(np.array([0, 0, 0]), np.array([2, 0, 0]), buff=0)
-            >>> arrow.tip.base.round(2)
+            >>> arrow.tip.base.round(2) + 0.  # add 0. to avoid negative 0 in output
             array([1.65, 0.  , 0.  ])
 
         """
@@ -946,7 +946,7 @@ def tip_point(self):
         --------
         ::
             >>> arrow = Arrow(np.array([0, 0, 0]), np.array([2, 0, 0]), buff=0)
-            >>> arrow.tip.tip_point.round(2)
+            >>> arrow.tip.tip_point.round(2) + 0.
             array([2., 0., 0.])
 
         """
@@ -960,7 +960,7 @@ def vector(self):
         --------
         ::
             >>> arrow = Arrow(np.array([0, 0, 0]), np.array([2, 2, 0]), buff=0)
-            >>> arrow.tip.vector.round(2)
+            >>> arrow.tip.vector.round(2) + 0.
             array([0.25, 0.25, 0.  ])
 
         """