BE 내 정보 조회의 http method를 수정한다

[hwanfront]

router.post('/info', checkAuthenticated, async (req, res, next) => { ... }

router.get('/info', checkAuthenticated, async (req, res, next) => { ... }

Originally posted by @asdfg32145 in https://github.com/hwanfront/rnt-sales/pull/14#pullrequestreview-1611597248