.gitattributes: update lock file attributes (#515379)

**/deps.nix linguist-generated

# node/js lock files

**/package-lock.json linguist-generated

**/yarn.nix linguist-generated

**/yarn.lock linguist-generated

# Rust lock files

**/Cargo.lock linguist-generated

pkgs/build-support/rust/**/Cargo.lock -linguist-generated

# NuGet, Gradle and others

**/deps.json linguist-generated

# Ruby lock files

**/gemset.nix linguist-generated

**/Gemfile.lock linguist-generated

# PHP lock files

**/composer.lock linguist-generated

# various package managers and tools

**/deps.nix linguist-generated

**/deps.toml linguist-generated

**/node-packages.nix linguist-generated

pkgs/applications/editors/emacs-modes/*-generated.nix linguist-generated

pkgs/development/r-modules/*-packages.nix linguist-generated