feat: add contest clone API endpoint

contest/urls/admin.py

@@ -1,9 +1,10 @@
 from django.urls import path
 
-from ..views.admin import ACMContestHelper, ContestAnnouncementAPI, ContestAPI, DownloadContestSubmissions
+from ..views.admin import ACMContestHelper, ContestAnnouncementAPI, ContestAPI, ContestCloneAPI, DownloadContestSubmissions
 
 urlpatterns = [
     path("contest", ContestAPI.as_view()),
+    path("contest/clone", ContestCloneAPI.as_view()),
     path("contest/announcement", ContestAnnouncementAPI.as_view()),
     path("contest/acm_helper", ACMContestHelper.as_view()),
     path("download_submissions", DownloadContestSubmissions.as_view()),