Fix bundle install path to use absolute path

Use absolute path for vendor/bundle to prevent bundler from creating
directories relative to BUNDLE_GEMFILE location (gemfiles/vendor/).

This fixes untracked file errors in Ruby 2.7 CI runs.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

.github/workflows/ruby.yml

@@ -57,7 +57,7 @@ jobs:
           path: vendor/bundle
           key: root-gem-cache-${{ matrix.ruby }}-${{ hashFiles('Gemfile.lock') }}
       - name: Install Ruby Gems
-        run: bundle check --path=vendor/bundle || bundle _2.4.9_ install --path=vendor/bundle --jobs=4 --retry=3
+        run: bundle check --path=${{ github.workspace }}/vendor/bundle || bundle _2.4.9_ install --path=${{ github.workspace }}/vendor/bundle --jobs=4 --retry=3
       - run: yarn
       - run: bundle exec rake react:update
       - run: bundle exec rake ujs:update