0.27.0

Breaking Changes:

• The minium supported Rust version was bumped to 1.57.0 due to requirements from dependencies. (#472)
• Add the rust-version field to the manifest. (#473)
• Update to edition 2021. (#473)

Features:

• Implement Envelope::from_path and Envelope::from_slice. (#456)
• Add basic attachment support. (#466)

Internal:

• Replace ancient lazy_static crate with once_cell or const slices. (#471)

Thank you:

Features, fixes, and improvements in this release have been contributed by:

• @MarijnS95
• @timfish