test : add unit tests for fetchIssuesMetrics function

[tmdeveloper007]

Summary of What Needs to be Done:
Add unit tests for the fetchIssuesMetrics function in src/lib/github.ts. Tests must use vitest framework and import actual source code.

Changes that Need to be Made:

• Create test using vitest describe/it/expect
• Import fetchIssuesMetrics from src/lib/github.ts
• Test returns IssuesMetrics structure
• Test calculates correct totals and trends

Impact that it would Provide:

• Ensures issue metrics calculation is correct
• Validates trend calculation logic

[Harsh-Codes-77]

/assign

[github-actions]

✅ Closed as completed!

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