Update sphinx-copybutton requirement in /requirements (#23)

Updates the requirements on [sphinx-copybutton](https://github.com/executablebooks/sphinx-copybutton) to permit the latest version.
- [Release notes](https://github.com/executablebooks/sphinx-copybutton/releases)
- [Changelog](https://github.com/executablebooks/sphinx-copybutton/blob/master/CHANGELOG.md)
- [Commits](executablebooks/sphinx-copybutton@v0.5.0...v0.5.2)

---
updated-dependencies:
- dependency-name: sphinx-copybutton
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements/docs.txt

@@ -1,6 +1,6 @@
 sphinx~=7.2.0
 sphinx-autobuild==2021.3.14
-sphinx-copybutton~=0.5.0
+sphinx-copybutton~=0.5.2
 furo==2023.9.10
 enum-tools[sphinx]~=0.11.0
 sphinx-design[furo]~=0.5.0