add string formatting symbol

Author: makeajourney

pandas/io/parsers.py

@@ -2563,7 +2563,7 @@ def _infer_columns(self):
 
                         while cur_count > 0:
                             counts[col] = cur_count + 1
-                            col = '{column}.{count}'.format(
+                            col = '{column!s}.{count}'.format(
                                 column=col, count=cur_count)
                             cur_count = counts[col]