Fix conflict with resolv-replace gem (#989)

* Fix conflict with resolv-replace gem

Closes #987

In version 3.2.7 socket_timeout option was introduced for TCPSocket.

This works unless `resolv-replace` gem is loaded (which was added to
ruby standard library since version 3.0.0).

This commit adds another check besides the ruby version check to avoid
breaking dalli for applications that have `resolv-replace` gem required.

* Fix rubocop warning

* Comment additional check in TCP.open method definition

lib/dalli/socket.rb

@@ -88,7 +88,14 @@ class TCP < TCPSocket
       # options - supports enhanced logging in the case of a timeout
       attr_accessor :options
 
-      if RUBY_VERSION >= '3.0'
+      # Check that TCPSocket#initialize was not overwritten by resolv-replace gem
+      # (part of ruby standard library since 3.0.0, should be removed in 3.4.0),
+      # as it does not handle keyword arguments correctly.
+      # To check this we are using the fact that resolv-replace
+      # aliases TCPSocket#initialize method to #original_resolv_initialize.
+      # https://github.com/ruby/resolv-replace/blob/v0.1.1/lib/resolv-replace.rb#L8
+      if RUBY_VERSION >= '3.0' &&
+         !::TCPSocket.private_instance_methods.include?(:original_resolv_initialize)
         def self.open(host, port, options = {})
           sock = new(host, port, connect_timeout: options[:socket_timeout])
           sock.options = { host: host, port: port }.merge(options)