Update plugin org.springframework.boot to v3.4.4

Author: renovate[bot]

build.gradle

@@ -1,6 +1,6 @@
 plugins {
     id 'java'
-    id 'org.springframework.boot' version '3.4.2'
+    id 'org.springframework.boot' version '3.4.4'
     id 'io.spring.dependency-management' version '1.1.7'
     id 'checkstyle'
 }