Update pytest-xdist requirement from <3.3,>=2.1.0 to >=2.1.0,<3.4 (#6155)

Updates the requirements on [pytest-xdist](https://github.com/pytest-dev/pytest-xdist) to permit the latest version.
- [Changelog](https://github.com/pytest-dev/pytest-xdist/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest-xdist/compare/v2.1.0...v3.3.1)

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

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

pyproject.toml

@@ -68,7 +68,7 @@ dev = [
     "pytest-asyncio>=0.17,<0.22",
     "pytest-cov>=2.7.1,<4.1",
     "pytest-timeout>=1.3.3,<2.2",
-    "pytest-xdist>=2.1.0,<3.3",
+    "pytest-xdist>=2.1.0,<3.4",
     "pytest>=6.1.0,<8",
     "requests>=2.9.1,<3",
     "tox>=3.5,<5",