feat: make reset_voiddate into a bang method

app/models/lettings_log.rb

@@ -26,7 +26,7 @@ class LettingsLog < Log
   before_validation :reset_scheme_location!, if: :scheme_changed?, unless: :location_changed?
   before_validation :process_postcode_changes!, if: :postcode_full_changed?
   before_validation :process_previous_postcode_changes!, if: :ppostcode_full_changed?
-  before_validation :reset_voiddate, if: :startdate_changed?
+  before_validation :reset_voiddate!, if: :startdate_changed?
   before_validation :reset_invalidated_dependent_fields!
   before_validation :reset_location_fields!, unless: :postcode_known?
   before_validation :reset_previous_location_fields!, unless: :previous_postcode_known?
@@ -540,7 +540,7 @@ private
     end
   end
 
-  def reset_voiddate
+  def reset_voiddate!
     validate_property_void_date(self)
     if errors[:voiddate].present? && unresolved?
       self.voiddate = nil