[FIX] website_blog: Latest Posts

On the website, when the widget "Latest Posts - Big Images" or "Latest
Posts - List" is added a 404 error is raised in the console.

This is because the regular expression of the background image is too
'greedy' and also match the trailing double quote, e.g.:
`website_blog.blog_post_cover_02"` instead of
`website_blog.blog_post_cover_02`.

By making it match the minimum pattern, the trailing double quote is not
selected.

opw-2061596

closes odoo/odoo#36622

X-original-commit: 0797a4ab90ec4d9be55e16d917da98909ce0ece4
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/website_blog/static/src/js/s_latest_posts_frontend.js

@@ -116,7 +116,7 @@ publicWidget.registry.js_get_posts = publicWidget.Widget.extend({
             $progress.appendTo($loadingContainer);
             $post.appendTo(self.$target);
 
-            var m = $thumb.css('background-image').match(/url\(["']?(.+)["']?\)/);
+            var m = $thumb.css('background-image').match(/url\(["']?(.+?)["']?\)/);
             var bg = m ? m[1] : 'none';
             var loaded = false;