Make sure we always have a good path.

The path wasn't right when running tests, because our working directory wasn't /spiffworkflow-backend

src/spiffworkflow_backend/services/logging_service.py

@@ -132,7 +132,7 @@ def setup_logger(app: Flask) -> None:
 
     spiff_logger_filehandler = None
     if app.config["SPIFFWORKFLOW_BACKEND_LOG_TO_FILE"]:
-        spiff_logger_filehandler = logging.FileHandler(f"log/{app.env}.log")
+        spiff_logger_filehandler = logging.FileHandler(f"{app.root_path}/../../log/{app.env}.log")
         spiff_logger_filehandler.setLevel(spiff_log_level)
         spiff_logger_filehandler.setFormatter(log_formatter)