mybatis-spring-boot-2.2.1

Here is the complete list of changes.

Dependencies Updates

• Switch base line version to Spring Boot 2.6 #591
• Upgrade to Spring Boot 2.6.2 #608
• Update to mybatis 3.5.9 #610
• Update to kotlin 1.6.0 #587 (using at sample)
• Update to groovy 3.0.9 #579 (using at sample)