docs: Remove dephell badge from Readme

[jamesholland-uk]

Description

Remove the badge for "dephell" from the repo's Readme

Motivation and Context

Dephell has been deprecated and it has just been removed it from the release workflow

How Has This Been Tested?

N/A

Screenshots (if appropriate)

Types of changes

• Docs

Checklist

• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes if appropriate.
• [ ] All new and existing tests passed.