Checked the release notes and could not find that i has been removed. I get

 Could not set unknown property 'cveValidForHours' for extension 'dependencyCheck' of type org.owasp.dependencycheck.gradle.extension.DependencyCheckExtension

by setting

dependencyCheck {
    cveValidForHours = 24
}

This used to work in 8.x and as far as i check the docs https://jeremylong.github.io/DependencyCheck/dependency-check-gradle/configuration.html i find

dependencyCheck {
    autoUpdate=false
    cveValidForHours=1
    format='ALL'
}

I see there is nvd.validForHours and hostedSuppressions.validForHours which might be the way to now replace the value above? Could someone clarify? Thank you!