Apply Spring Boot gradle plugin (#328)
Apply Spring Boot gradle plugin (#328)

This commit changes below version internally.
okhttp: 3.9.0 -> 3.14.9
fluent-hc: 4.4.1 -> 4.5.13
yanagishima/yanagishima,yanagishima/yanagishima,yanagishima/yanagishima,yanagishima/yanagishima