Upgrade to Groovy 5.0.3

See:

• https://groovy-lang.org/releasenotes/groovy-5.0.html and especially https://groovy-lang.org/releasenotes/groovy-5.0.html#Groovy5.0-breaking for the breaking changes
• https://groovy-lang.org/changelogs/changelog-5.0.0.html
• https://groovy-lang.org/changelogs/changelog-5.0.1.html
• https://groovy-lang.org/changelogs/changelog-5.0.2.html
• https://groovy-lang.org/changelogs/changelog-5.0.3.html

As usually, it would be safer to wait for a new cycle for this upgrade. So that means XWiki 18.0.0.