Fix ConnectionPool.new to use keyword arguments for Ruby 3.4

Ruby 3.4 changed how hash-to-keyword argument conversion works.
Changed from passing a hash as a positional argument to explicit
keyword arguments to ensure compatibility.

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

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

Author: justin808

react_on_rails/lib/react_on_rails/server_rendering_pool/ruby_embedded_java_script.rb

@@ -9,11 +9,10 @@ module ServerRenderingPool
     class RubyEmbeddedJavaScript
       class << self
         def reset_pool
-          options = {
+          @js_context_pool = ConnectionPool.new(
             size: ReactOnRails.configuration.server_renderer_pool_size,
             timeout: ReactOnRails.configuration.server_renderer_timeout
-          }
-          @js_context_pool = ConnectionPool.new(options) { create_js_context }
+          ) { create_js_context }
         end
 
         def reset_pool_if_server_bundle_was_modified