fix: update URL validation to handle GitHub URLs properly

[devin-ai-integration]

Fix URL validation in PR check script to properly handle GitHub URLs.

The current validation was causing false negatives for valid URLs. This fix:

• Updates URL validation to use simple protocol check
• Adds test cases to verify GitHub URL handling
• Maintains security by requiring https:// or http:// prefix

Testing:

• Added unit tests for URL validation
• Verified locally with pr-check script
• Tested with existing valid packages

[github-actions]

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[github-actions]

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[devin-ai-integration]

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