Bump node from 14-alpine to 15-alpine in /test/json-server
Bump node from 14-alpine to 15-alpine in /test/json-server

Bumps node from 14-alpine to 15-alpine.

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
yasuyuky/ghteam-auth,yasuyuky/ghteam-auth