Make sure stroke width is always a float

Author: 3b1b

manimlib/mobject/types/vectorized_mobject.py

@@ -127,7 +127,7 @@ def set_stroke(self, color=None, width=None, opacity=None, background=None, recu
                 if isinstance(width, np.ndarray):
                     arr = width.reshape((len(width), 1))
                 else:
-                    arr = np.array([[w] for w in listify(width)])
+                    arr = np.array([[w] for w in listify(width)], dtype=float)
                 mob.data['stroke_width'] = arr
 
         if background is not None: