Remove sql header comments only in AR 5.0

This removal is performed by the parent method in AR >= 5.1

Author: tagliala

Diff for: lib/active_record/tasks/chronomodel_database_tasks.rb

@@ -24,7 +24,7 @@ def structure_dump(*arguments)
         sql = File.read(filename).gsub(/CREATE SCHEMA (?!IF NOT EXISTS)/, '\&IF NOT EXISTS ')
         File.open(filename, 'w') { |file| file << sql }
 
-        remove_sql_header_comments(filename)
+        remove_sql_header_comments(filename) if ActiveRecord::VERSION::STRING < '5.1'
       end
 
       def data_dump(target)