Use Display for formatter parse errors (#9316)

## Summary

This helps a bit with (but does not close) the issues described in
https://github.com/astral-sh/ruff/issues/9311. E.g., now, we at least
see: `error: Failed to format main.py: source contains syntax errors:
invalid syntax. Got unexpected token '=' at byte offset 20`.

crates/ruff_python_parser/src/parser.rs

@@ -305,12 +305,6 @@ impl fmt::Display for ParseError {
     }
 }
 
-impl ParseError {
-    pub fn error(self) -> ParseErrorType {
-        self.error
-    }
-}
-
 /// Represents the different types of errors that can occur during parsing.
 #[derive(Debug, PartialEq)]
 pub enum ParseErrorType {