Update robotframework-robocop requirement from >=8.4.1 to >=8.6.0

Updates the requirements on [robotframework-robocop](https://github.com/MarketSquare/robotframework-robocop) to permit the latest version.
- [Release notes](https://github.com/MarketSquare/robotframework-robocop/releases)
- [Commits](MarketSquare/robotframework-robocop@v8.4.1...v8.6.0)

---
updated-dependencies:
- dependency-name: robotframework-robocop
  dependency-version: 8.6.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

requirements-dev.txt

@@ -4,7 +4,7 @@ pytest-cov
 pytest-mockito
 robotstatuschecker
 ruff >= 0.16.1
-robotframework-robocop >= 8.4.1
+robotframework-robocop >= 8.6.0
 invoke >= 3.0.3
 twine
 wheel