Soft incompatibility with requested beautifulsoup4

[stefan6419846]

When doing pip install commoncode in a restricted environment or when upgrading from a version < 32, a warning is raised:

WARNING: beautifulsoup4 4.12.2 does not provide the extra 'chardet'

According to the upstream project, beautifulsoup4>=4.12.3 is required for this option: https://bugs.launchpad.net/beautifulsoup/+bug/2019018

At least during some quick testing, this did not cause any failures, although only doing some rather limited test runs for now. Nevertheless, this does not look correct.