Update pytest-xdist requirement from ~=3.4 to ~=3.5 (#9265)

Updates the requirements on [pytest-xdist](https://github.com/pytest-dev/pytest-xdist) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest-xdist/releases)
- [Changelog](https://github.com/pytest-dev/pytest-xdist/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-xdist@v3.4.0...v3.5.0)

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

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

Author: dependabot[bot]

requirements_test.txt

@@ -4,7 +4,7 @@ tbump~=6.11.0
 contributors-txt>=1.0.0
 pytest-cov~=4.1
 pytest-profiling~=1.7
-pytest-xdist~=3.4
+pytest-xdist~=3.5
 six
 # Type packages for mypy
 types-pkg_resources==0.1.3