update: modify rubocop installation in CI workflow and add it as a development dependency

Author: FarhanAnjum-opti

.github/workflows/ruby.yml

@@ -33,16 +33,14 @@ jobs:
       with:
         ruby-version: ${{ matrix.ruby }}
         bundler-cache: true
-    - name: Install rubocop conditionally based on Ruby version
+    - name: Install rubocop conditionally in Gemfile
       run: |
         echo "Ruby version: ${{ matrix.ruby }}"
         if [[ "${{ matrix.ruby }}" == "3.0.0" ]]; then
-          echo "Installing rubocop 1.78.0 for Ruby 3.0.0"
-          gem install rubocop -v 1.78.0
-        else
-          echo "Installing latest rubocop"
-          gem install rubocop
+          echo "Adding rubocop 1.78.0 to Gemfile"
+          bundle add rubocop --version 1.78.0 || true
         fi
+        bundle install
     - name: Run linting
       run: |
         bundle exec rubocop

optimizely-sdk.gemspec

@@ -25,6 +25,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'coveralls_reborn'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'rspec'
+  spec.add_development_dependency 'rubocop'
   spec.add_development_dependency 'webmock'
 
   spec.add_runtime_dependency 'json-schema', '>= 2.6'