extism 1.8.0 on Rust Cargo

What's Changed

Fix: no method named free found for mutable reference &mut current_plugin::CurrentPlugin in the current scope by @billythedummy in #773
fix(plugin_call): set rc to EXIT_SIGNALED_SIGABRT when wasmtime bails out on plugin call by @G4Vi in #776
feat: add ability to access response headers when using extism:host/env::http_request by @zshipko in #774
fix: use f32::to_bits and f64::to_bits when constructing Val by @zshipko in #779
Add codeowners file by @bhelx in #780

Full Changelog: v1.7.0...v1.8.0