tests: removed unused import and fix operating on closed transaction …

…inside context manager bug

tests/test_job_database.py

@@ -222,7 +222,7 @@ def test_update_one_media(setup_database):
         # Get the media with the name vid3.mp4 and update the timestamp and status to SUCCESS
         update_media(db, job, 'vid3.mp4', Status.SUCCESS)
 
-    # with session_maker.begin() as db:
+    with session_maker.begin() as db:
         media = db.query(Media).filter(Media.name == 'vid3.mp4').first()
 
         # Verify that the number of medias is the same, except a newer timestamp