Update pytest requirement from >=7.0.0 to >=9.1.1 (#18)

Updates the requirements on [pytest](https://github.com/pytest-dev/pytest) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@7.0.0...9.1.1)

---
updated-dependencies:
- dependency-name: pytest
  dependency-version: 9.1.1
  dependency-type: direct:development
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements-dev.txt

@@ -1,7 +1,7 @@
 # Development dependencies
 
 # Testing framework
-pytest>=7.0.0
+pytest>=9.1.1
 pytest-cov>=4.0.0
 pytest-asyncio>=0.21.0