fix: issues affecting code quality (#1420)

* use `delegate` for delegation
* Time should be used with zone

lib/shoulda/matchers/action_controller/flash_store.rb

@@ -1,3 +1,4 @@
+require 'active_support/core_ext/module/delegation'
 module Shoulda
   module Matchers
     module ActionController
@@ -34,10 +35,7 @@ module Shoulda
             expected_value === actual_value
           end
         end
-
-        def empty?
-          flash.empty?
-        end
+        delegate :empty?, to: :flash
 
         def use_now!
           @use_now = true

lib/shoulda/matchers/active_model/validate_absence_of_matcher.rb

@@ -113,7 +113,7 @@ module Shoulda
             case column_type
             when :integer, :float then 1
             when :decimal then BigDecimal(1, 0)
-            when :datetime, :time, :timestamp then Time.now
+            when :datetime, :time, :timestamp then Time.current
             when :date then Date.new
             when :binary then '0'
             else 'an arbitrary value'