devel/difftastic: update to 0.54.0

0.54 (released 7th January 2024)
Parsing
- Added support for Salesforce Apex.
- Improved parsing of regex literals in Clojure and strictness annotations
  in Haskell.

Diffing
- Difftastic will now also report file permission changes.
- Fixed an issue where directory diffing would show a file more than once.

Display
- Fixed a rare crash when the last non-blank line had changes for certain
  parsers, particularly YAML.

Command Line Interface
- Difftastic now errors if given a single path, unless that file contains
  conflict markers. Previously this was a warning.

Build
- Difftastic now requires Rust 1.63 to build.

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