build(deps): Bump pytest-xvfb in /testing/plugins_integration (#13302)

Bumps [pytest-xvfb](https://github.com/The-Compiler/pytest-xvfb) from 3.0.0 to 3.1.1.
- [Changelog](https://github.com/The-Compiler/pytest-xvfb/blob/master/CHANGELOG.rst)
- [Commits](The-Compiler/pytest-xvfb@v3.0.0...v3.1.1)

---
updated-dependencies:
- dependency-name: pytest-xvfb
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

testing/plugins_integration/requirements.txt

@@ -12,4 +12,4 @@ pytest-sugar==1.0.0
 pytest-trio==0.8.0
 pytest-twisted==1.14.3
 twisted==24.11.0
-pytest-xvfb==3.0.0
+pytest-xvfb==3.1.1