Update pytest-xdist requirement from ~=2.4 to ~=2.5

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@v2.4.0...v2.5.0)

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

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

Author: dependabot[bot]

requirements_test.txt

@@ -7,7 +7,7 @@ tbump~=6.6.0
 pyenchant~=3.2
 pytest-cov~=3.0
 pytest-profiling~=1.7
-pytest-xdist~=2.4
+pytest-xdist~=2.5
 # Type packages for mypy
 types-pkg_resources==0.1.3
 types-toml==0.10.1