Compatibility with Python-3.13

[Dominic König]

Hello everyone--

as some of you have noted, there is a compability issue with Python-3.13:

As usual, we want to support the last two Debian versions and the Python
versions they ship with, which means Python-3.9 (for Debian-11 bullseye) and
Python-3.11 (for Debian-12 bookworm) for now. Debian-13 Trixie will ship with
Python-3.12, so that will be the next stage.

However, several other OS Environment ship with Python-3.13, and as a major
change in that version the cgi module has been dropped from the standard
library - but web2py-2 still depends on it.

Web2py-3.0 does no longer use cgi, but it also requires Python-3.11 or later,
so wouldn't be compatible with Debian-11. Tests also show that web2py-3.0 is
still somewhat unstable and buggy, so in order to maintain stability and
continued support for Debian-11 (and hence, Python-3.9), we will delay the
move to web2py-3 until Debian-13 is available.

That also means, that we still need the cgi module, and therefore you would
run into these compatibility issues with Python-3.13. There is though an easy
workaround, which is that on Python-3.13 you would install the legacy-cgi
module separately:

pip install legacy-cgi

...which is a fork of the original cgi module intended for extended support of
existing cgi-based implementations.

I will make an effort to purge the remaining cgi references from the Eden ASP
code base (which is unproblematic), and prepare for web2py-3 - but until we
can drop support for Python-3.9, we will still need web2py-2 and therefore
cgi.

Dominic