Several of these have been fixed, so let's update the requirement if
necessary and remove the warning catching.
`python-dateutil 2.9.0` was released Feb 29, 2024, so it's not widely
packaged in non-EOL major distros yet.
`pytest-cov 4.1.0` was released May 24, 2023.
Our pinned versions were already higher than these requirements.
Alternatively, we could just remove the warnings and not update the
minimum requirement, but I think it's nicer to note it in requirements
for anyone running our tests, like packagers.
We already require `poetry-plugin-export>=1.9.0`. `1.7.0` updated its
`requests-toolbelt` requirement to `>=1.0.0`, which is greater than the
minimum version needed to remove the warning.
Part of https://github.com/certbot/certbot/issues/10403
We were never actually updating the versions in certbot-ci and letstest.
Not that it really matters, but let's do that there as well.
