fix : 동일 멘토 멘티 중복 신청 불가능하도록 수정#563

lsy1307 merged 3 commits intosolid-connection:developsolid-connection/solid-connect-server:developfrom

lsy1307:fix/557-mentoring-uk-settinglsy1307/solid-connect-server:fix/557-mentoring-uk-settingCopy head branch name to clipboard