Bump selenium from 4.20.0 to 4.21.0

Bumps [selenium](https://github.com/SeleniumHQ/Selenium) from 4.20.0 to 4.21.0.
- [Release notes](https://github.com/SeleniumHQ/Selenium/releases)
- [Commits](SeleniumHQ/selenium@selenium-4.20.0...selenium-4.21.0)

---
updated-dependencies:
- dependency-name: selenium
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

devel.txt

@@ -8,5 +8,5 @@ twine
 readme_renderer[md]
 robotframework
 robotframework-seleniumlibrary
-selenium==4.20.0
+selenium==4.21.0
 wheel