Skip GitHub OAuth spec

What does this MR do?

Skips the GitHub OAuth spec instead of quarantine as continuously running the test may cause the user to hit GitHub's limits causing the test user to be permanently blocked.

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content