Arrow3D issue in `__init__` for `--renderer=opengl`

[chaithyagr]

Description of bug / unexpected behavior

I try to run OpenGL as renderer for Arrow3D and I see the issue that the default strokewidth is 0.5, which is a float and not interable:

manim/lib/python3.10/site-packages/manim/mobject/opengl/opengl_v │
│ ectorized_mobject.py:413 in has_stroke                                                           │
│                                                                                                  │
│    410 │   │   return (                                                                          │
│    411 │   │   │   stroke_widths is not None                                                     │
│    412 │   │   │   and stroke_opacities is not None                                              │
│ ❱  413 │   │   │   and any(stroke_widths)                                                        │
│    414 │   │   │   and any(stroke_opacities)                                                     │
│    415 │   │   )                                                                                 │
│    416                                                                                           │
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
TypeError: 'float' object is not iterable

Code for reproducing the problem

arrow = Arrow3D(
                start=start_location,
                end=end_location,
                resolution=RES,
                color=color,
        )

This can be tackled by making https://github.com/ManimCommunity/manim/blob/27011d648f8a0fe0d79fd9187b21083a4009a940/manim/mobject/three_d/three_dimensions.py#L109 to :

        stroke_width: list = [0.5],

However, I am sure this is cosmetic and not the actual fix.