Update tomcat and springboot versions and don't register purge tasks without atrifactory properties

[labkey-susanh]

Rationale

• Adjust versions for a minor CVE related to the tomcat version
• Gradle plugins version 7.2.0 adjusted the PurgeX tasks to be more compatible with Gradle best practices, but that introduced a reliance on the artifactory authentication properties those tasks depend on. Since those tasks do require the user name, password, and contextURL, we check for the existence of all those properties before registering the purge tasks.

Changes

• Tomcat and springBoot version updates
• update to build.gradle to conditionalize the registration of the PurgeX tasks.