Update repo structure as part of nixification

.github/workflows/ruby.yml

@@ -1,20 +0,0 @@
-name: Ruby
-on:
-  pull_request:
-
-jobs:
-  ruby_testing:
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ubuntu-latest, macos-latest]
-        # Due to https://github.com/actions/runner/issues/849, we have to use quotes for '3.0'
-        ruby: ['2.6', '2.7', '3.0', '3.1']
-    runs-on: ${{ matrix.os }}
-    steps:
-    - uses: actions/checkout@v3
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-        bundler-cache: true # runs 'bundle install' and caches installed gems automatically
-    - run: bundle exec rake tests