(V4) - Tied a release candidate to our dependencies

[StijnKas]

pdstools version checks

• [X] I have checked that this issue has not already been reported.

• [X] I have confirmed this bug exists on the latest version of pdstools.

Issue description

Because Plotly V6 doesn't depend on Pandas anymore, I'm tying our V4 on it. However, it's not formally released yet - only under a release candidate.

Reproducible example

Install pdstools[adm]

Expected behavior

Once Plotly V6 formally releases, we should remove the rc tag

Installed versions

Replace this line with the output of pdstools.show_versions(), leave the backticks in place