added missing interface implimentation

Signed-off-by: Neil South <neil.south@answerdigital.com>

Author: neildsouth

src/Plugins/AWSS3/StorageAdminService.cs

@@ -34,5 +34,6 @@ public class StorageAdminService : IStorageAdminService
         public Task<bool> HasConnectionAsync() => throw new NotImplementedException();
 
         public Task RemoveUserAsync(string username) => throw new NotImplementedException();
+        public Task<bool> SetConnectionAsync() => throw new NotImplementedException();
     }
 }