chore(deps): update dependency pytest-cov to v6.3.0 (#846)

This PR contains the following updates:

| Package | Change | Age | Confidence |
|---|---|---|---|
| [pytest-cov](https://redirect.github.com/pytest-dev/pytest-cov)
([changelog](https://pytest-cov.readthedocs.io/en/latest/changelog.html))
| `==6.2.1` -> `==6.3.0` |
[![age](https://developer.mend.io/api/mc/badges/age/pypi/pytest-cov/6.3.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/pytest-cov/6.2.1/6.3.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>pytest-dev/pytest-cov (pytest-cov)</summary>

###
[`v6.3.0`](https://redirect.github.com/pytest-dev/pytest-cov/blob/HEAD/CHANGELOG.rst#630-2025-09-06)

[Compare
Source](https://redirect.github.com/pytest-dev/pytest-cov/compare/v6.2.1...v6.3.0)

- Added support for markdown reports.
Contributed by Marcos Boger in `#&#8203;712
<https://github.com/pytest-dev/pytest-cov/pull/712>`\_
and `#&#8203;714 <https://github.com/pytest-dev/pytest-cov/pull/714>`\_.
- Fixed some formatting issues in docs.
Anonymous contribution in `#&#8203;706
<https://github.com/pytest-dev/pytest-cov/pull/706>`\_.

</details>

---

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requirements-test.txt

@@ -1,6 +1,6 @@
 pytest==8.4.2
 pytest-pep8==1.0.6
-pytest-cov==6.2.1
+pytest-cov==6.3.0
 pytest-aiohttp==1.1.0
 pytest-asyncio==1.1.0
 responses==0.25.8