chore(deps-dev): bump pytest from 8.4.2 to 9.1.1

Bumps [pytest](https://github.com/pytest-dev/pytest) from 8.4.2 to 9.1.1.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@8.4.2...9.1.1)

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

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

Author: dependabot[bot]

poetry.lock

@@ -40,7 +40,7 @@ Issues = "https://github.com/ActiveCampaign/postmark-python/issues"
 packages = [{ include = "postmark" }]
 
 [tool.poetry.group.dev.dependencies]
-pytest = "^8.1.1"             # Testing framework
+pytest = "^9.1.1"             # Testing framework
 pytest-asyncio = "^1.0.0"     # To run async tests with pytest
 respx = "^0.21.0"             # Mocking HTTP requests for testing
 pytest-cov = "^7.0.0"         # For coverage reports