changed to lowercase string type

api/Repositories/IPersonRepository.cs

@@ -6,9 +6,9 @@ namespace api.Repositories
     public interface IPersonRepository
     {
         Task<IEnumerable<Person>> GetAllAsync();
-        Task<Person> GetByUsernameAsync(String username);
+        Task<Person> GetByUsernameAsync(string username);
         Task AddAsync(Person person);
         Task UpdateAsync(Person person);
-        Task DeleteAsync(String username);
+        Task DeleteAsync(string username);
     }
 }