Use `squish` rather than `strip_heredoc`

activerecord/lib/active_record/persistence.rb

@@ -480,10 +480,10 @@ def reload(options = nil)
     #
     def touch(*names, time: nil)
       unless persisted?
-        raise ActiveRecordError, <<-end_error.strip_heredoc
+        raise ActiveRecordError, <<-MSG.squish
           cannot touch on a new or destroyed record object. Consider using
           persisted?, new_record?, or destroyed? before touching
-        end_error
+        MSG
       end
 
       time ||= current_time_from_proper_timezone

activerecord/lib/active_record/touch_later.rb

@@ -9,10 +9,10 @@ module TouchLater
 
     def touch_later(*names) # :nodoc:
       unless persisted?
-        raise ActiveRecordError, <<-end_error.strip_heredoc
+        raise ActiveRecordError, <<-MSG.squish
           cannot touch on a new or destroyed record object. Consider using
           persisted?, new_record?, or destroyed? before touching
-        end_error
+        MSG
       end
 
       @_defer_touch_attrs ||= timestamp_attributes_for_update_in_model