Update gitea go-sdk to v0.15.0 (#385)

Update "code.gitea.io/sdk/gitea" to latest release

Reviewed-on: https://gitea.com/gitea/tea/pulls/385
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-committed-by: 6543 <6543@obermui.de>

vendor/code.gitea.io/sdk/gitea/repo_migrate.go

@@ -47,6 +47,8 @@ type MigrateRepoOption struct {
 	PullRequests   bool           `json:"pull_requests"`
 	Releases       bool           `json:"releases"`
 	MirrorInterval string         `json:"mirror_interval"`
+	LFS            bool           `json:"lfs"`
+	LFSEndpoint    string         `json:"lfs_endpoint"`
 }
 
 // Validate the MigrateRepoOption struct