v0.4.0

• Update to new kittage backend for kitty-protocol-supporting terminals (fixes many issues and improves performance significantly, see the PR)
• Use new mupdf search API for slightly better performance
• Update ratatui(-image) dependencies
• Allow specification of default white and black colors for rendered pdfs
• Pause rendering every once in a while while there's a search term to enable searching across the entire document more quickly
• Fix an issue with missing search highlights