chore: Release version 0.4.0

[mkroening]

Release notes:

🚀 Features

• Add virtio-blk definitions
• Upgrade to spec 1.4
• (virtio-mmio) Add MAGIC_VALUE constant
• (features) Add recommendations and recommendations_satisfied
• (features) Remove FeatureBits bounds that are not elaborated
• (features) Seal FeatureBits
• (features) Remove requirements() and recommendations()
• Don't derive zerocopy traits for volatile structs
• Rename virtio::Id::IoMem to Iomem to match reference name
• Make enums ABI-compatible
• (net) Make hash header contain the normal header

🐛 Bug Fixes

• (virtq) Clippy::manual_is_multiple_of
• (docsrs) Migrate from doc_auto_cfg to doc_cfg
• Rust-2018-idioms
• Upgrade to Rust 2024
• (mmio) Support multiple doc aliases in macro_rules!

📚 Documentation

• (features) Clarify driver and device requirements
• Mark Entropy Device as supported
• (balloon) Add module-level doc comment
• Add aliases to virtio::Id
• (features) Update virtio::F docs to spec 1.4

⚙️ Miscellaneous Tasks

• Run cargo-semver-checks
• (Cargo.toml) Remove deprecated package.authors field
• Use Cargo build.warnings instead of RUSTFLAGS=-Dwarnings

💼 Other

• (deps) Update allocator-api2 to 0.4
• (deps) Upgrade bitfield-struct to 0.13