add github ci tests

Dependencies

• [2] CLXEECMF * Start putting build results in a database.

Change contents

• file addition: .github (d--r------)
  [2.2]
• file addition: workflows (d--r------)
  [0.1]
• file addition: test.yml (----------)
  [0.22]
  + name: "Test"

  + on:

  + pull_request:

  + push:

  + jobs:

  + tests:

  + runs-on: ubuntu-18.04

  + steps:

  + - uses: actions/checkout@v2

  + with:

  + fetch-depth: 0

  + - uses: cachix/install-nix-action@v8

  + #- run: nix flake check

  + - run: nix-build -A checks.x86_64-linux