Fix bug where repositories appear unadopted (#15757) (#15767)

Fix bug where repositories with capital letters in their names appear unadopted.

Fix #15755

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/repository/adopt.go

@@ -228,7 +228,7 @@ func ListUnadoptedRepositories(query string, opts *models.ListOptions) ([]string
 					found := false
 				repoLoop:
 					for i, repo := range repos {
-						if repo.Name == name {
+						if repo.LowerName == name {
 							found = true
 							repos = append(repos[:i], repos[i+1:]...)
 							break repoLoop