fix: replace bare open() calls with context managers in cardiology_detect.py

[rtmalikian]

Problem

pyhealth/tasks/cardiology_detect.py uses bare open().readlines() calls in 5 places (lines 76, 172, 266, 360, 454). These rely on CPython reference counting for file handle cleanup, which is not guaranteed across all Python implementations.

Solution

Replace label_content = open(path, "r").readlines() with:

with open(path, "r") as f:
    label_content = f.readlines()

Affected Files

• pyhealth/tasks/cardiology_detect.py (5 occurrences)