Update version. Downgrade JDK

[rnc]

Updates parent to 21 and main web-commons-bom to 30.

This downgrades the JDK bytecode target from 11 -> 8. The reason for this is Atlas is used heavily by both PME (pom-manipulator) and GME (gradle-manipulator). For GME, the plugins have to run in both alignment environment (which is >= 11) and the build environment (which can be >= 8). Therefore we need this to have JDK8 bytecode. I can override the logback version using Gradle's strict version resolution mechanism as the version in web-commons-bom is >= 11 only.

[ligangty]

Maybe we should use an alternative branch to add a classifier like "-jdk8" to give a jdk8 compatible release but not use master branch. @rnc @sswguo @ruhan1 WDYT?

[rnc]

Maybe we should use an alternative branch to add a classifier like "-jdk8" to give a jdk8 compatible release but not use master branch. @rnc @sswguo @ruhan1 WDYT?

I would argue against this. It would increase maintenance IMHO for little benefit. There is no current byte code constraints in Atlas requiring a higher JDK from what I can see. Compiling to a lower JDK level does not prevent any other projects with higher JDK requirements from using it. By using JDK8 this allows PME/GME to use it and eliminate CVE issues that the older version of Atlas faces. Also, adding a classifier then complicates the situation even more as libraries within PNC use it without any classifier. It would then be difficult to combine libraries from PNC inside the Bacon project with libraries from PME i.e. Bacon would end up depending upon two Atlas libraries - one with the classifier and one without.

[ligangty]

@rnc Ok sounds good. Approved and merged.