Upgrade to Rust 2021 - increase major number of hermit-abi because this release requires 2021 edition of Rust - yank previous version => all previous versions are able to use older 2018 edition
Upgrade to Rust 2021 - increase major number of hermit-abi because this release requires 2021 edition of Rust - yank previous version => all previous versions are able to use older 2018 edition