Remove unused imports across multiple files to clean up the codebase

tests/test_backup.py

@@ -8,7 +8,6 @@ from __future__ import annotations
 
 import hashlib
 
-import pytest
 
 from tests.conftest import auth_header, TEST_USER_IDS
 
@@ -168,7 +167,7 @@ class TestDeleteBackup:
     def _get_backup_id(self, client, tier="power") -> str:
         """Upload a backup and return its DB id from history."""
         _upload(client, tier=tier)
-        history = client.get(
+        client.get(
             "/api/v1/backup/history", headers=auth_header(tier)
         ).json()
         # History returns BackupMetadata schema which doesn't have `id`.