Feat- Add github icon to navbar

[Biki-das]

What kind of change does this PR introduce?

Replaced the Plain Github label link text with the Github Icon.

Issue Number:

Fixes #403

Did you add tests for your changes?

No

Snapshots/Videos:

https://user-images.githubusercontent.com/72331432/224105939-698abb86-5956-4358-b8e3-7c7cb3eb9087.mp4

If relevant, did you update the documentation?

Summary

Does this PR introduce a breaking change?

No

Other information

Have you read the contributing guide?

Yes

[Cioppolo14]

@Biki-das Can you give a screenshot of this in dark mode?

[Biki-das]

@Biki-das Can you give a screenshot of this in dark mode?

sure @Cioppolo14