Revise export.cfg example for export/import setup

[DinisDimitris]

Updated the example configuration for export.cfg to include necessary packages and versions for export/import functionality.

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📚 Documentation preview 📚: https://plone-training--990.org.readthedocs.build/

[DinisDimitris]

The versions specified in the current docs do not work with Plone 4.3. I have fought long battles with dependency hell here, so I hope this will help people in the future having troubles with the installation on a plone 4.3 site.