Fix JRuby 10.1 compatibility in supports_connect_timeout?

JRuby 10.1.0.0 (Ruby 4.0 compat) does not support instance_method on
its Java-backed TCPSocket, causing NoMethodError on every connection
attempt. Guard the introspection with RUBY_ENGINE == 'ruby' so JRuby
falls back to Timeout.timeout, consistent with the existing MRI-specific
skip guard in the test.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: petergoldstein

lib/dalli/socket.rb

@@ -112,7 +112,7 @@ def self.open(host, port, options = {})
       def self.supports_connect_timeout?
         return @supports_connect_timeout if defined?(@supports_connect_timeout)
 
-        @supports_connect_timeout = RUBY_VERSION >= '3.0' &&
+        @supports_connect_timeout = RUBY_ENGINE == 'ruby' && RUBY_VERSION >= '3.0' &&
                                     ::TCPSocket.instance_method(:initialize).parameters == TCPSOCKET_NATIVE_PARAMETERS
       end
       # rubocop:enable ThreadSafety/ClassInstanceVariable

test/test_socket.rb

@@ -40,6 +40,7 @@
 
     it 'detects when TCPSocket#initialize parameters have changed' do
       skip 'Ruby 3.0+ required' if RUBY_VERSION < '3.0'
+      skip 'MRI-specific test' if RUBY_ENGINE != 'ruby'
 
       # Get the expected native parameters
       native_params = [[:rest]]