Prefer forwarding shorthand syntax on Ruby 2.7 and later

In rails/rails#38034 the `save` definition in `ActiveRecord::Validations`
was changed from an options hash to keyword arguments to prevent warnings
on Ruby 2.7. To prevent future changes to method signatures causing
issues use the forwarding shorthand syntax available in 2.7 and later.

lib/globalize.rb

@@ -17,6 +17,9 @@ module Globalize
   ACTIVE_RECORD_60 = Gem::Version.new('6.0.0')
   ACTIVE_RECORD_61 = Gem::Version.new('6.1.0')
 
+  CURRENT_RUBY     = Gem::Version.new(RUBY_VERSION)
+  RUBY_VERSION_27  = Gem::Version.new('2.7.0')
+
   class << self
     def locale
       read_locale || I18n.locale
@@ -64,6 +67,10 @@ def storage
       RequestStore.store
     end
 
+    def ruby_27?
+      CURRENT_RUBY >= RUBY_VERSION_27
+    end
+
     def rails_42?
       ::ActiveRecord.version < ACTIVE_RECORD_50
     end

lib/globalize/active_record/instance_methods.rb

@@ -158,9 +158,8 @@ def globalize_fallbacks(locale)
         Globalize.fallbacks(locale)
       end
 
-      if Globalize.rails_61?
-        # Rails 6.1 and later has removed positional arguments which were never used
-        def save(**)
+      if Globalize.ruby_27?
+        def save(...)
           result = Globalize.with_locale(translation.locale || I18n.default_locale) do
             without_fallbacks do
               super