chore(deps): update plugin org.springframework.boot to v4

Ref: PACT-445

Author: pactflow-renovate-bot[bot]

build.gradle

@@ -1,5 +1,5 @@
 plugins {
-	id 'org.springframework.boot' version '3.5.7'
+	id 'org.springframework.boot' version '4.0.0'
 	id 'io.spring.dependency-management' version '1.1.7'
 	id 'java'
 }