add cov package

Author: LinearParadox

pyproject.toml

@@ -25,6 +25,7 @@ dev = [
     "mypy-extensions>=1.0.0",
     "pandas-stubs>=2.2.3.250308",
     "pytest>=8.3.5",
+    "pytest-cov>=6.1.1",
     "ruff>=0.11.5",
     "scanpy>=1.11.1",
     "scipy-stubs>=1.15.2.1",