Python 3.13: Replace cgi module

[bgermann]

Describe the bug
PEP 594 has led to the removal of the cgi module in Python 3.13.
spyne makes use of that module.

To Reproduce
Running the test suite fails with
E ModuleNotFoundError: No module named 'cgi'

Additional context
This was reported as Debian bug #1082317.

[bgermann]

@t-8ch You probably want to fix this to keep Elbe building with Debian trixie.

[kavdev]

For anyone still running into this, you can install the legacy-cgi python package to get this working again.