update nix, add rubocop #25

	name: Run tests
	on:
	pull_request:
	branches:
	- "master"
	push:
	branches:
	- "master"

	# We also provide a way to run this manually, if needed.
	workflow_dispatch:

	jobs:
	ci:
	runs-on: ubuntu-22.04
	steps:
	- name: Install Nix
	uses: cachix/install-nix-action@v30
	with:
	github_access_token: ${{ secrets.GITHUB_TOKEN }}

	- name: Check out repository code
	uses: actions/checkout@v4
	with:
	fetch-depth: 0

	- name: Run tests
	run: nix develop --command rspec

	- name: Run rubocop
	run: nix develop --command rubocop

	- name: Run nix formatter
	run: nix fmt -- --check .

Provide feedback