feat(gpodder_sqlite): add user admin field

gpodder_sqlite/src/repository/auth.rs

@@ -18,6 +18,7 @@ impl From<User> for gpodder::User {
             id: value.id,
             username: value.username,
             password_hash: value.password_hash,
+            admin: value.admin,
         }
     }
 }