Add unexpectedly dropped BUNDLE_WITHOUT again

Follow #200

.github/workflows/spec.yml

@@ -30,21 +30,18 @@ jobs:
     runs-on: ${{ matrix.os }}
     env: # $BUNDLE_GEMFILE must be set at the job level, so it is set for all steps
       BUNDLE_GEMFILE: ${{ github.workspace }}/${{ matrix.gemfile }}
+      # https://github.com/kachick/irb-power_assert/blob/104834846baf5caa1e8536a11c43acdd56fc849c/CONTRIBUTING.md#adding-dependencies-for-this-gem
+      BUNDLE_WITHOUT: development
     steps:
       - name: Install libyaml
         if: startsWith(matrix.os, 'ubuntu-')
         run: sudo apt-get install --no-install-recommends --assume-yes libyaml-dev
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
-        env:
-          # https://github.com/kachick/irb-power_assert/blob/104834846baf5caa1e8536a11c43acdd56fc849c/CONTRIBUTING.md#adding-dependencies-for-this-gem
-          BUNDLE_WITHOUT: development
         with:
           ruby-version: ${{ matrix.ruby }}
           # Enabling is the recommended way, but it cannot detect runner changes in early stage.
           # So disable it is better for test job, do not mind in other jobs
           bundler-cache: false # runs 'bundle install' and caches installed gems automatically
       - run: bundle install
       - run: bundle exec rake spec
-        env:
-          BUNDLE_WITHOUT: development