fix: Java Toolchain 설정 추가 (Java 17) (#198)

* fix: Java Toolchain 설정 추가 (Java 17)

* fix: Java 17 소스 호환성 설정 제거

Author: jayn2u

build.gradle

@@ -4,9 +4,14 @@ plugins {
     id 'io.spring.dependency-management' version '1.1.0'
 }
 
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(17))
+    }
+}
+
 group = 'ssu'
 version = '0.0.1-SNAPSHOT'
-sourceCompatibility = '17'
 
 bootJar {
     archivesBaseName = 'EatSsu'