In the source code for that page you can find the following piece of code:
<script>
var sFlix = document.createElement('script');
sFlix.setAttribute('type', 'text/javascript');
sFlix.setAttribute('src', '//media.flixfacts.com/js/loader.js');
sFlix.setAttribute('data-flix-distributor', '7148');
sFlix.setAttribute('data-flix-language', 'tr');
sFlix.setAttribute('data-flix-brand', Storm.DataLayer.data.user.productBrand.toLowerCase());
sFlix.setAttribute('data-flix-ean', Storm.DataLayer.data.user.ean);
sFlix.setAttribute('data-flix-sku', Storm.DataLayer.data.user.productId);
sFlix.setAttribute('data-flix-inpage', 'flix-inpage');
document.getElementsByTagName('head')[0].appendChild(sFlix);
setTimeout(function(){ $(document).trigger('fee.fgrid_refresh'); }, 2000);
setTimeout(function(){ $(document).trigger('fee.fgrid_refresh'); }, 4000);
setTimeout(function(){ $(document).trigger('fee.fgrid_refresh'); }, 6000);
setTimeout(function(){ $(document).trigger('fee.fgrid_refresh'); }, 20000);
$('#flix-inpage').load(function() {
$(document).trigger('fee.fgrid_refresh');
});
setTimeout(function(){ $(document).trigger('fee.fgrid_refresh'); }, 40000);
</script>
which means the script tag you are looking for is not actually in the received response, it's created dynamically. In order to extract the information you need, you should query the source of the data-flix-ean attribute, the Storm.DataLayer object:
response.xpath('/html/head/script/text()').re(r"Storm.DataLayer.put\('ean','(.*)'\);")