build(deps-dev): update pytest-cov requirement from ^4.0 to ^6.0

Updates the requirements on [pytest-cov](https://github.com/pytest-dev/pytest-cov) to permit the latest version.
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-cov@v4.0.0...v6.0.0)

---
updated-dependencies:
- dependency-name: pytest-cov
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -31,7 +31,7 @@ lsp = ["pygls"]
 
 [tool.poetry.dev-dependencies]
 pytest = "^8.0"
-pytest-cov = "^4.0"
+pytest-cov = "^6.0"
 pytest-console-scripts = "^1.4"
 sphinx = "^7.2.6"
 sphinx-rtd-theme = "^2.0.0"