Release v0.4.0

What's Changed

• Add sixel_rs::sixel_string for encoding image bytes to a string
• Add usage examples
  • encode-file: uses Encoder struct
  • encode-bytes: uses sixel_string
• Mention similar projects in README.md

Full Changelog: v0.3.3...v0.4.0

Release v0.3.3

Security

• Fix RUSTSEC-2022-0013
• Fix RUSTSEC-2022-0006

Maintenance

• Remove unused dependencies
  • directly related to the advisory reports that are mentioned in the previous section

CI/CD

• Add continuous integration/deployment workflows

Refactor

• Switch to Rust 2021 edition
• Apply clippy suggestions
• Format code using rustfmt
• Clean up codebase

Full Changelog: v0.3.1...v0.3.3