fix: enum type 소문자 직렬화로 변경

src/main/java/com/aolda/itda/config/LoggingFilter.java

...n/java/com/aolda/itda/controller/main/MainController.java

src/main/java/com/aolda/itda/dto/main/MainInfoDTO.java

...ain/java/com/aolda/itda/entity/certificate/Challenge.java

src/main/java/com/aolda/itda/entity/log/Action.java

src/main/java/com/aolda/itda/entity/log/ObjectType.java

src/main/java/com/aolda/itda/service/main/MainService.java

src/main/resources/logback-spring.xml