Text Error On non-English languages

### Describe the error

I recently installed manimgl on an env of Annaconda using python3.9.
And met with this problem when trying to relize the last example in #680

### Code and Error
**Code**:

```
from manimlib import *

script = '''
Hello
你好
こんにちは
안녕하세요
'''

class Demo(Scene):
def construct(self):
text = Text(script, font='Source Han Sans')
self.play(Write(text))
```
is what the .py

then `manimgl ***.py Demo`

**Error**:

```
ManimGL v1.6.1
[20:23:00] WARNING You may be using Windows platform and have not specified the path of config.py:232
`temporary_storage`, which may cause OSError. So it is recommended to specify the
`temporary_storage` in the config file (.yml)
Traceback (most recent call last):
File "D:\Programming\Anaconda3\envs\manim\Scripts\manimgl-script.py", line 33, in
sys.exit(load_entry_point('manimgl', 'console_scripts', 'manimgl')())
File "c:\users\unrul\manim\manimlib\__main__.py", line 25, in main
scene.run()
File "c:\users\unrul\manim\manimlib\scene\scene.py", line 91, in run
self.construct()
File "ppw.py", line 35, in construct
text = Text(script, font='Source Han Sans')
File "c:\users\unrul\manim\manimlib\mobject\svg\text_mobject.py", line 149, in __init__
super().__init__(text, **kwargs)
File "c:\users\unrul\manim\manimlib\mobject\svg\labelled_string.py", line 65, in __init__
self.post_parse()
File "c:\users\unrul\manim\manimlib\mobject\svg\labelled_string.py", line 122, in post_parse
self.group_items = self.get_group_items()
File "c:\users\unrul\manim\manimlib\mobject\svg\labelled_string.py", line 414, in get_group_items
ordered_spans = [
File "c:\users\unrul\manim\manimlib\mobject\svg\labelled_string.py", line 415, in
self.label_span_list[label] if label != -1 else self.full_span
IndexError: list index out of range

```
### Environment
**win 10**:
**manim 1.6.1**: master
**python 3.9**:

And actually, after I tried, it happens every time when I try to put any non-English languages in the `Text`, and all ended up the same `IndexError: list index out of range `

Can I get any help?