[Copilot AI] Async test style inconsistency in test_create_gitlab_mr.py

[nexiouscaliver]

Problem

test_create_gitlab_mr.py uses legacy asyncio.get_event_loop().run_until_complete() while the rest of the test suite uses asyncio.run().

Fix

Standardize to asyncio.run() across all test files.

Identified by Copilot AI agent.