convert.py: sys.stderr.write --> logger.error

Author: mofosyne

convert.py

@@ -1434,7 +1434,7 @@ def default_outfile(model_paths: list[Path], file_type: GGMLFileType) -> Path:
     }[file_type]
     ret = model_paths[0].parent / f"ggml-model-{namestr}.gguf"
     if ret in model_paths:
-        sys.stderr.write(
+        logger.error(
             f"Error: Default output path ({ret}) would overwrite the input. "
             "Please explicitly specify a path using --outfile.\n")
         sys.exit(1)