Bump Psych code point limit if possible

JRuby's YAML backend, SnakeYAML, has a default codepoint limit to
prevent large content from leading to a DOS. The limit needs to be
increased here to allow it to propagate through the rest of the
test, or it will raise too early and fail.

See ruby/psych#647

Author: headius

spec/ruby_llm/chat_error_spec.rb

@@ -69,6 +69,10 @@
 
         it 'handles context length exceeded errors' do # rubocop:disable RSpec/ExampleLength,RSpec/MultipleExpectations
           skip('Ollama does not throw an error for context length exceeded') if provider == :ollama
+
+          # Configure Psych to allow large input (JRuby's ext provider SnakeYAML has a low limit by default)
+          Psych::Parser.code_point_limit = 20_000_000 if Psych::Parser.respond_to?(:code_point_limit=)
+
           # Create a huge conversation
           massive_text = 'a' * 1_000_000