Yoko OYAMA

### Description Fixes garbled UTF-8 characters after formatting. tdiff:diff_files/2 returns the diff in raw string, so simple list_to_binary/1 is required when converting it into binary. Currently, ```erlang %% （・ω・） ```...

**Describe the bug** UTF-8 characters get garbled after formatting. **To Reproduce** Have a piece of unformatted code and/or comment that includes multibyte UTF-8 characters, then trigger code formatting. E.g. ```erlang...