ci: add a downstream tailwindcss-rails integration test

Author: flavorjones

.github/workflows/downstream.yml

@@ -25,16 +25,19 @@ jobs:
       matrix:
         include:
           - url: https://github.com/rails/tailwindcss-rails
-            name: tailwindcss-rails
+            name: rails-unit
             command: "bin/test"
             ruby: "3.3"
+          - url: https://github.com/rails/tailwindcss-rails
+            name: rails-integration
+            command: "env TAILWINDCSSOPTS=--path=../../.. test/integration/user_journey_test.sh"
+            ruby: "3.3"
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{matrix.ruby}}
-      - run: gem install bundler -v ">= 2.3.22" # for "add --path"
       - run: bundle install --local || bundle install
       - run: bundle exec rake download
       - run: git clone --depth=1 ${{matrix.url}} ${{matrix.name}}