Remove usages of the lowercase h in GitHub

[kfcampbell]

This is another one of the small items that have been bothering me for a little bit.

---

Behavior

Before the change?

• Logs and comments that included the GitHub company name were variously spelled "GitHub" and "Github", the second of which is incorrect.

After the change?

• All logs and comments spelled "Github" have been corrected to "GitHub".

Other information

• N/A

---

Additional info

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Added the appropriate label for the given change

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes (Please add the Type: Breaking change label)
• No

If Yes, what's the impact:

• N/A

---