First PR here 👋 Still trying to figure out the process.
I calculated the hashes by executing this bash

version="2.0.0-RC6-4"
nix-prefetch-url "https://raw.githubusercontent.com/coursier/coursier/v${version}/modules/cli/src/main/resources/completions/zsh"
nix-prefetch-url "https://github.com/coursier/coursier/releases/download/v${version}/coursier"

and copying the hash from the output of each command.

Motivation for this change

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.