Update the Behat tests: Redmine 6.0.2 and 5.1.5 released

[github-actions]

These 2 maintenance releases are available for download, you can review the changes in the Changelog.
Version 6.0.2 includes important fixes:

• Time entry API (#41819) and CSV export (#41895) return `hours` as Rational instead of Float
• Projects endpoint ignores offset and limit params and returns list of all projects (#41791)
• Plugin activity cannot show icons after switching to SVG icons (#41880)
• Multiple fixes related to the migration from legacy icons to SVG icons

Both versions include a fix for the following warning during startup: "Unresolved or ambiguous specs during Gem::Specification.reset" ([#41749](https://www.redmine.org/issues/41749 "Defect: Warning during startup: "Unresolved or ambiguous specs during Gem::Specification.reset" (Closed)")).

We strongly recommend updating to Redmine 6.0.2.

Thanks everyone for the effort to report and fix all these issues.

https://www.redmine.org/news/149