manim: Changing fonts in "Text" does not work

Hi, maybe it is only on my system (Ubuntu 20.04), but using this example:

class Example5Text(Scene):
        def construct(self):
            text = Text('Hello world', font='Source Han Sans').scale(3)
            self.add(text)

should give this result: (image is taken from https://github.com/3b1b/manim/pull/680) However, when I run it on my machine, it only renders the text with the default font. To distinguish the default font from Source Han Sans, note that the “ll” has no small arc at the bottom in the default font.