Release 3.4.0

Update libraries:
Vaadin to 25.3.0 S
Spring-boot to 4.0.0
Lombok to 1.18.46
Variable-field to 2.0.1
Spring-openapi to 3.1.1
Hsqldb to 2.7.4
flyway to 13.8.1
jackson to 3.2.3