Add fedora dependency install command (Dnf)

[JensTimmerman]

Proposed change

Add command to install dependencies in fedora (using dnf) (relevant since testing page already contains this command for fedora: https://developers.home-assistant.io/docs/development_testing/ )

Type of change

• [X] Document existing features within Home Assistant
• [ ] Document new or changing features which there is an existing pull request elsewhere
• [ ] Spelling or grammatical corrections, or rewording for improved clarity
• [ ] Changes to the backend of this documentation
• [ ] Removed stale or deprecated documentation

Additional information

• This PR fixes or closes issue: fixes #
• Link to relevant existing code or pull request: