extism 1.4.0 on Rust Cargo

What's Changed

refactor: remove HttpRequest.header alias by @mhmd-azeez in #718
doc: update API.md for latest changes by @zshipko in #720
chore: rename kernel/.cargo/config to kernel/.cargo/config.toml by @zshipko in #721
fix: re-use linking code from Plugin::new in Plugin::reset_store by @zshipko in #722
refactor!: update to wasmtime 20 or greater by @zshipko in #723
fix(libextism): examples and docs by @G4Vi in #724
fix: return error when non-zero exit code in returned by @zshipko in #727
fix(libextism): improve static linking pkgconfig by @G4Vi in #726

Full Changelog: v1.3.0...v1.4.0