title: How to add remarks to existing column using liquibase
body: <p>I'm working in posgresql database, and I want to overwrite an existing comment in a column of a table using liquibase, so I have : 
   <code>mytable (column1 int) --This is a comment</code></p>
  
  <p>I know that I can do it in a SQL native way, like this:</p>
  
  <pre><code>&lt;changeSet author="myuser" id="123456"&gt;
          &lt;sql dbms="postgresql"&gt;
              COMMENT ON COLUMN mytable.column1 IS 'This is my new comment';
          &lt;/sql&gt;
  &lt;/changeSet&gt;
  </code></pre>
  
  <p>Is there any way to make this change without relying on a native mechanism?</p>