fix: add name fallback for GitHub users

[Bricklou]

🔗 Linked issue

150

❓ Type of change

Ensure users will always have a name, even if no display name is defined on their GitHub account. This is done by doing a fallback on the login name.

• [x] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality like performance)
• [ ] ✨ New feature (a non-breaking change that adds functionality)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Resolves #150

📝 Checklist

• [x] I have linked an issue or discussion.
• [ ] I have updated the documentation accordingly.

[RomainLanz]

Thanks!