Update flake8-rst-docstrings requirement from <0.3,>=0.2 to >=0.2,<0.4

Updates the requirements on [flake8-rst-docstrings](https://github.com/peterjc/flake8-rst-docstrings) to permit the latest version.
- [Release notes](https://github.com/peterjc/flake8-rst-docstrings/releases)
- [Commits](peterjc/flake8-rst-docstrings@v0.2.0...v0.3.0)

---
updated-dependencies:
- dependency-name: flake8-rst-docstrings
  dependency-type: direct:development
...

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

Author: dependabot[bot]

setup.py

@@ -72,7 +72,7 @@
             "flake8-builtins>=1.5,<3",  # Avoid shadowing Python built-in names
             "flake8-colors>=0.1,<0.2",  # Produce colorful error / warning output
             "flake8-docstrings>=1.5,<2",  # Ensure docstrings are formatted well
-            "flake8-rst-docstrings>=0.2,<0.3",  # Allow use of ReST in docstrings
+            "flake8-rst-docstrings>=0.2,<0.4",  # Allow use of ReST in docstrings
             "flake8-use-fstring>=1,<2",  # Highlight use of old-style string formatting
             "mccabe>=0.6,<0.8",  # Checks that code isn't overly complicated
             "pandas>=1.4,<1.6",