Update pydocstyle requirement from <4.0 to <7.0 (#2528)

Updates the requirements on [pydocstyle](https://github.com/PyCQA/pydocstyle) to permit the latest version.
- [Release notes](https://github.com/PyCQA/pydocstyle/releases)
- [Changelog](https://github.com/PyCQA/pydocstyle/blob/master/docs/release_notes.rst)
- [Commits](PyCQA/pydocstyle@0.1.0...6.3.0)

---
updated-dependencies:
- dependency-name: pydocstyle
  dependency-type: direct:development
...

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

dev-requirements.txt

@@ -4,7 +4,7 @@ flake8-docstrings
 nose
 pep8
 pyflakes
-pydocstyle<4.0
+pydocstyle<7.0
 httmock==1.4.0
 watchdog==0.9.0
 wooper==0.4.4