Keep null values in oemetadata

[jh-RLI]

Summary of the discussion

Only merge if OpenEnergyPlatform/omi#72 is available on pypi

As described in #1273, removing null / none values causes confusion and should therefore not be done by the platform.

This is related to a change in omi that was introduced to give the user control over whether to omit null values. This functionality now retains null values by default.

Type of change (CHANGELOG.md)

Updated

• The oemetadata on the oep is now stored including null / none values. Users reported that it otherwise is confusing and hinders there metadata workflow. This is related to the update in omi v0.2.0 (PR#1541)

Workflow checklist

Automation

Closes #1273
Closes #1108

PR-Assignee

• 🐙 Follow the workflow in CONTRIBUTING.md
• 📝 Update the CHANGELOG.md
• 📙 Update the documentation on mkdocs

Reviewer

• 🐙 Follow the Reviewer Guidelines
• 🐙 Provided feedback and show sufficient appreciation for the work done