chore(deps): update pytest-qgis requirement in /requirements

Updates the requirements on [pytest-qgis](https://github.com/GispoCoding/pytest-qgis) to permit the latest version.
- [Release notes](https://github.com/GispoCoding/pytest-qgis/releases)
- [Changelog](https://github.com/GispoCoding/pytest-qgis/blob/main/CHANGELOG.md)
- [Commits](GispoCoding/pytest-qgis@v2.0.0...v2.1.0)

---
updated-dependencies:
- dependency-name: pytest-qgis
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements/testing.txt

@@ -2,5 +2,5 @@
 # --------------------
 
 pytest-cov>=4
-pytest-qgis>=2,<2.1
+pytest-qgis>=2.1.0,<2.2
 packaging>=23