reinstate use of utils.misc.is_dev_mode() in driver code

this was removed during rebase/merge in previous commit

src/pds/registrysweepers/driver.py

@@ -68,12 +68,14 @@
 from pds.registrysweepers.utils.db.client import get_opensearch_client_from_environment
 from pds.registrysweepers.utils.misc import get_human_readable_elapsed_since
 
+from src.pds.registrysweepers.utils.misc import is_dev_mode
+
 
 def run():
     configure_logging(filepath=None, log_level=logging.INFO)
     log = logging.getLogger(__name__)
 
-    dev_mode = str(os.environ.get("DEV_MODE")).lower() not in {'none', '', '0', 'false'}
+    dev_mode = is_dev_mode()
     if dev_mode:
         log.warning('Operating in development mode - host verification disabled')
         import urllib3