Use min Rust version but test beta and nightly
Use min Rust version but test beta and nightly

nix-rust/nix,geofft/nix-rust,berkowski/nix,berkowski/nix,xd009642/nix,geofft/nix-rust,MarkusJais/nix-rust,carllerche/nix-rust,asomers/nix,carllerche/nix-rust,MarkusJais/nix-rust,kamalmarhubi/nix-rust,carllerche/nix-rust,berkowski/nix,xd009642/nix,kamalmarhubi/nix-rust,geofft/nix-rust,Susurrus/nix,asomers/nix,nix-rust/nix,xd009642/nix,kamalmarhubi/nix-rust,Susurrus/nix,MarkusJais/nix-rust,Susurrus/nix