Merge pull request rails#50545 from santib/use-all-ci-cores

Parallelize tests in the CI

Author: rafaelfranca

railties/lib/rails/generators/rails/app/templates/github/ci.yml.tt

@@ -92,6 +92,9 @@ jobs:
           ruby-version: .ruby-version
           bundler-cache: true
 
+      - name: Configure parallelization
+        run: echo "PARALLEL_WORKERS=$(nproc)" >> $GITHUB_ENV
+
       - name: Run tests
         env:
           RAILS_ENV: test