[migration] mark all version prior 3.7 as non-migrable
API possible used by such old migration script are not supported in recent
Cubiweb.
Closes #2772958
<div id="ajaxroot">
<div class="ajaxHtmlHead">
<script src="http://foo.js" type="text/javascript"> </script>
<link rel="stylesheet" type="text/css" media="all" href="qunit.css" />
</div>
<h1>Hello</h1>
</div>