style: fix ruff format in conftest.py

Add missing blank line between the _set_timestamp_defaults helper
and the next top-level constant so `ruff format --check .` passes.
Pre-existing on dev's HEAD; surfaced after rebasing PR #39 onto dev
in 2b20946.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

tests/conftest.py

@@ -27,6 +27,7 @@ def _set_timestamp_defaults(mapper, connection, target):
         if getattr(target, col.key, None) is None:
             setattr(target, col.key, now)
 
+
 TEST_JWT_SECRET = secrets.token_urlsafe(32)
 TEST_SERVICE_KEY = secrets.token_urlsafe(32)
 TEST_FERNET_KEY = "7reF42nmTwbdN21PBoubGp7h_FU8qSimstmlaMLoRK8="