Add support for Python 3.12

[pbauer]

No description provided.

[gforcada]

@pbauer do we want to add 3.12 support to Plone 6.0 first? 🤔 the jobs I created on Jenkins are for Plone 6.1, but adding them for Plone 6.0 should not be a problem 👍🏾

[gforcada]

@pbauer robotframework-browser has already a 3.12 compatible release 🎉 I updated this PR to be on top of 6.0 branch, so we get plone.api and plone.restapi fixed master branches. This should make this PR pass 🍀

[gforcada]

@mauritsvanrees the GHA Create only instance and test with Buildout fails due to robotframework-browser having a dependency on click but click version pin is only on versions-extra.cfg.

[mauritsvanrees]

@mauritsvanrees the GHA Create only instance and test with Buildout fails due to robotframework-browser having a dependency on click but click version pin is only on versions-extra.cfg.

This is exactly the kind of problem that this test is supposed to catch: click (and its dependencies) are now pulled in by Plone (or tests), so this version should be in versions.cfg.
I will move the pin. Trying it out locally first. Takes a while, as lots of packages need to be downloaded and/or compiled on 3.12 for the first time.

In 6.1 we could choose to use just one versions file. But for 6.0 we should stick to what we have.

[mauritsvanrees]

That worked. Let's try Jenkins for good measure.

@jenkins-plone-org please run jobs