v4.21.0

Support for Liquibase 4.21.0.

What's Changed

• Bump maven-compiler-plugin from 3.10.1 to 3.11.0 by @dependabot in #124
• Bump liquibase-maven-plugin from 4.19.0 to 4.20.0 by @dependabot in #126
• Bump liquibase-maven-plugin from 4.20.0 to 4.21.0 by @dependabot in #127

Full Changelog: liquibase-vertica-4.20.0...liquibase-vertica-4.21.0