fix introduced bug from rubocop edits in Standards.ThermalZone.rb

prior commit changed
      if prior_rules.size == 0
to
      if prior_rules.size.empty?
when it should be
      if prior_rules.empty?

lib/openstudio-standards/standards/Standards.ThermalZone.rb

@@ -510,7 +510,7 @@ def spaces_get_occupancy_schedule(spaces, sch_name: nil, occupied_percentage_thr
     # todo - also merging non adjacent priority rules without getting rid of any rules between the two could create unexpected reults
     prior_rules = []
     sch_ruleset.scheduleRules.each do |rule|
-      if prior_rules.size.empty?
+      if prior_rules.empty?
         prior_rules << rule
         next
       else