Update dependency pytest-cov to v6

pyproject.toml

@@ -25,7 +25,7 @@ optional-dependencies.dev = [
     "ipdb>=0.13.13,<1",
     "pandas-stubs>=2.2.3,<3",
     "mypy>=1.11.2,<2",
-    "pytest-cov>=5.0.0,<6",
+    "pytest-cov>=6,<7",
     "pytest-random-order>=1.1.1,<2",
     "pytest-xdist>=3.6.1,<4",
     "pytest>=8.3.3,<9",