Pin python3-platformdirs & python3-virtualenv to 22.04 versions, for Python 2 on Ubuntu 23.10+ ? [try apt instead of pip, for KA Lite]

[holta]

This PR is essentially what @jvonau outlined at:

• pin virtualenv to version in U22.04 #3583 (comment)

I suppose only time will tell (with Ubuntu 24.04 LTS about 11 months away) if this more long-winded apt approach is either (A) safer... or (B) more fragile... than the pip approach implemented by:

• PR 'pip install virtualenv==20.21.1' for Python 2 required by KA Lite on Ubuntu 23.10 #3582

Related:

• PR notes and dependencies [for Python 2 on new OS's on {amd64, arm64, armhf}. Tested on Debian 12 & Ubuntu 23.04] #3535

[holta]

FYI this approach works with KA Lite, when tested on Ubuntu 23.10:

root@u2310:~# virtualenv --version
virtualenv 20.13.0+ds from /usr/lib/python3/dist-packages/virtualenv/__init__.py

root@u2310:~# apt list virtualenv
Listing... Done
virtualenv/mantic 20.23.0+ds-1 all

root@u2310:~# apt list -a python3-platformdirs
Listing... Done
python3-platformdirs/mantic 3.5.0-1 all [upgradable from: 2.5.1-1]
python3-platformdirs/now 2.5.1-1 all [installed,upgradable to: 3.5.0-1]

root@u2310:~# apt list -a python3-virtualenv
Listing... Done
python3-virtualenv/mantic 20.23.0+ds-1 all [upgradable from: 20.13.0+ds-2]
python3-virtualenv/now 20.13.0+ds-2 all [installed,upgradable to: 20.23.0+ds-1]

This PR should also be tested on Debian 12 and Ubuntu 23.04, if this apt approach (whose version of virtualenv is about 16 months older than the pip approach) is strongly preferred.

[holta]

This PR is tested on Debian 12 Bookworm's near-final pre-release (KA Lite works).

Raspberry Pi OS 12 will be much more important of course — when that's released in a few short weeks:

• How to pre-test RasPiOS 12 [cffi, cryptography, lxml "wheels" for Python 3.11 now exist!] #3526

Finally: if this apt approach has legs, we might later improve it using a much more recent version of virtualenv from Ubuntu 23.04

[holta]

This PR and/or the PR #3582 approach seem to make most sense in preparing for Ubuntu 24.04 LTS.

Whereas either approach should really be simplified — to use virtualenv 20.17.1 (already works with Python 2) built into Debian 12 and Raspberry Pi OS 12 — for people running those "Bookworm" OS's:

https://packages.debian.org/bookworm/virtualenv

[holta]

Let's give this a shot.

All these rickety mechanisms to make KA Lite work for a couple more years in 2023-2025 will surely need to evolve.

On the positive side it does work, and lays a decent framework (including in-line docs) for the imminent crop of "Bookworm" OS's and hopefully Ubuntu 24.04 LTS after that.

@jvonau can these 2 warnings be cleaned up on Debian 12 Bookworm, or should we live with them for now?

W: GPG error: http://archive.ubuntu.com/ubuntu jammy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 871920D1991BC93C
W: GPG error: http://archive.ubuntu.com/ubuntu jammy-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 871920D1991BC93C

[holta]

@jvonau can these 2 warnings be cleaned up on Debian 12 Bookworm, or should we live with them for now?

These probably can be ignored. Either way, I'm happy to merge this in the coming ~24h, regardless what the future holds.