[v5.0.9-r0] TypeError: 'type' object is not subscriptable

[MaxGyver83]

Describe the bug

When I start the xpra server, I get this error:

$ xpra start :100
xpra main error:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/xpra/scripts/main.py", line 111, in main
    options, args = do_parse_cmdline(cmdline, defaults)
  File "/usr/lib/python3/dist-packages/xpra/scripts/parsing.py", line 1783, in do_parse_cmdline
    fixup_options(options)
  File "/usr/lib/python3/dist-packages/xpra/scripts/config.py", line 1581, in fixup_options
    fixup_encodings(options)
  File "/usr/lib/python3/dist-packages/xpra/scripts/config.py", line 1432, in fixup_encodings
    from xpra.codecs.codec_constants import PREFERRED_ENCODING_ORDER
  File "/usr/lib/python3/dist-packages/xpra/codecs/codec_constants.py", line 29, in <module>
    PREFERRED_REFRESH_ENCODING_ORDER: tuple[str, ...] = (
TypeError: 'type' object is not subscriptable

To Reproduce
Steps to reproduce the behavior:

1. xpra start :100

System Information (please complete the following information):

• Server OS: Ubuntu 20.04
• Xpra Server Version: xpra v5.0.9-r0

Additional context

I think this error started after the upgrade to version v5.0.9-r0.

[totaam]

Thanks, fixed by the commit above.
This only affects distributions with older python versions.

[MaxGyver83]

Wow, this was quick. Thank you!