chore[infra]: sentry 지원을 위한 스프링부트 버전 변경

Author: DooHyoJeong

backend/build.gradle

@@ -1,7 +1,7 @@
 plugins {
     id 'java'
-    id 'org.springframework.boot' version '3.5.5'
-    id 'io.spring.dependency-management' version '1.1.7'
+    id 'org.springframework.boot' version '3.3.3'
+    id 'io.spring.dependency-management' version '1.1.5'
 
     id("org.jetbrains.kotlin.jvm") version "1.9.25"
     id("com.google.devtools.ksp") version "1.9.25-1.0.20"