Update pydocstyle requirement from <6.3 to <6.4

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
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

dev-requirements.txt

@@ -1,6 +1,6 @@
 diff_cover < 7.5
 pylint < 2.16
-pydocstyle < 6.3
+pydocstyle < 6.4
 flake8-bugbear < 22.13
 tox < 3.29  # until tox-pyenv is updated for tox 4.x
 tox-pyenv < 1.2