Update dependency org.springframework.boot to v4

Author: renovate[bot]

gradle/libs.versions.toml

@@ -15,7 +15,7 @@ logback = '1.5.21'
 
 javafxplugin = '0.1.0'
 spring = '7.0.1'
-springframework-boot = '3.5.8'
+springframework-boot = '4.0.0'
 spring-dependency-management = '1.1.7'
 javafx = '26-ea+16'