Update dependencies and improve CI workflow

- Use strings instead of floats for uniformity
- Rename "deps" with "rails" for uniformity with Inherited Resources and
  Active Admin gems
- Update bundler
- Fix platforms

Author: tagliala

.github/workflows/ci.yml

@@ -15,10 +15,10 @@ jobs:
       matrix:
         ruby:
           - "3.0"
-          - 3.1
-          - 3.2
-          - 3.3
-        deps:
+          - "3.1"
+          - "3.2"
+          - "3.3"
+        rails:
           - rails_61
           - rails_70
           - rails_71
@@ -27,11 +27,11 @@ jobs:
       - name: Configure bundler (default)
         run: |
           echo "BUNDLE_GEMFILE=Gemfile" >> "$GITHUB_ENV"
-        if: matrix.deps == 'rails_71'
+        if: matrix.rails == 'rails_71'
       - name: Configure bundler (alternative)
         run: |
-          echo "BUNDLE_GEMFILE=gemfiles/${{ matrix.deps }}/Gemfile" >> "$GITHUB_ENV"
-        if: matrix.deps != 'rails_71'
+          echo "BUNDLE_GEMFILE=gemfiles/${{ matrix.rails }}/Gemfile" >> "$GITHUB_ENV"
+        if: matrix.rails != 'rails_71'
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
@@ -41,10 +41,10 @@ jobs:
           COVERAGE: true
         run: |
           bundle exec rspec
-          mv coverage/coverage.xml coverage/coverage-ruby-${{ matrix.ruby }}-${{ matrix.deps }}.xml
+          mv coverage/coverage.xml coverage/coverage-ruby-${{ matrix.ruby }}-${{ matrix.rails }}.xml
       - uses: actions/upload-artifact@v4
         with:
-          name: coverage-ruby-${{ matrix.ruby }}-${{ matrix.deps }}
+          name: coverage-ruby-${{ matrix.ruby }}-${{ matrix.rails }}
           path: coverage
           if-no-files-found: error