Fix typo: unspported -> unsupported

Author: delirious-lettuce

prompt_toolkit/formatted_text.py

@@ -374,7 +374,7 @@ def _parse_corot(self):
  style = self._create_style_string()
  break
  else:
- # Ignore unspported sequence.
+ # Ignore unsupported sequence.
  break
  else:
  # Add current character.