Upgrade Grails version on both Grails-based applications to 3.2.8

Of course, Grails 3.2.8 comes out the very next day after I upgraded to Grails 3.2.7.

Upgraded both Grails-based applications from 3.2.7 to 3.2.8. I had to upgrade the Gradle wrapper and update dependencies. So, I generated blank Grails 3.2.7 and 3.2.8 apps and compared key files as necessary.

• build.gradle
• gradle.properties
• grails-app/conf/application.yml
• grails-app/conf/logback.groovy
• settings.gradle