feat: 솜커톤 참가자 모집 API 요청 URL에 somkathon 추가

Author: hodoon

src/main/java/dmu/dasom/api/domain/somkathon/controller/SomParticipantController.java

@@ -18,7 +18,7 @@
 import java.util.List;
 
 @RestController
-@RequestMapping("/api/participant")
+@RequestMapping("/api/somkathon/participants")
 @RequiredArgsConstructor
 public class SomParticipantController {