Fix HAML in profiles/gpg_keys/index.html.haml

What does this MR do?

Fixes HAML in app/views/profiles/gpg_keys/index.html.haml to follow Layout/SpaceAfterColon and Layout/SpaceInsideHashLiteralBraces.

Part of #326884 (closed) and #23855

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have not included a changelog entry because ~"technical debt" .
• Code review guidelines
• Style guides
• Separation of EE specific content