Merge pull request #450 from kyum-q/refactor/change-cd

백엔드 CI JDK 설정 추가

.github/workflows/backend_ci.yml

@@ -23,6 +23,12 @@ jobs:
                 path: /h2-console
             datasource:
               url: jdbc:h2:mem:database" > backend/src/main/resources/application.yml
+    
+      - name: JDK 17 설정
+        uses: actions/setup-java@v4
+        with:
+          java-version: 17
+          distribution: temurin
 
       - name: 테스트 코드 실행
         run: ./gradlew test