Support Python 3.11

Debian bookworm ships with Python 3.11 and should be released before the end of 2023. It thus seems a good idea to make Software Heritage codebase compatible.

• swh-web needs to be updated to use Django 4.1 (swh/devel/swh-web#4734 (closed))
• swh-deposit needs to be updated to use Django 4.1 (swh/devel/swh-deposit#4626)
• aiohttp-utils used by swh-core is compatible since 3.2.1 (see also swh/infra/sysadm-environment#4766 (closed))