Fix localhost detection for URL redirect protection

[evankanderson]

Summary

It turns out that I was a bit too zealous on the redirect URL protection. Fixes https://github.com/mindersec/minder/pull/5282/files#r1913339896

Change Type

Mark the type of change your PR introduces:

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

I read the code, sorry!

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 56.611%. remained the same
when pulling 76f5016 on evankanderson:fix-redirect-protection
into 9b2ecaa on mindersec:main.