typo in annotation

modify `heruistic` to `heuristic` in line 660, `charcter` to `character` in line 661.

examples/run_squad.py

@@ -657,8 +657,8 @@ def get_final_text(pred_text, orig_text, do_lower_case, verbose_logging=False):
     #
     # What we really want to return is "Steve Smith".
     #
-    # Therefore, we have to apply a semi-complicated alignment heruistic between
-    # `pred_text` and `orig_text` to get a character-to-charcter alignment. This
+    # Therefore, we have to apply a semi-complicated alignment heuristic between
+    # `pred_text` and `orig_text` to get a character-to-character alignment. This
     # can fail in certain cases in which case we just return `orig_text`.
 
     def _strip_spaces(text):