fix student can't get sub detail

Author: zdszero

submission/models.py

@@ -38,7 +38,7 @@ class Submission(models.Model):
 
     def check_user_permission(self, user, check_share=True):
         if (
-            self.user_id == user.id
+            str(self.user_id) == str(user.id)
             or user.is_super_admin()
             or user.can_mgmt_all_problem()
             or self.problem.created_by_id == user.id