[FIX] website_blog: blog pager page issue

When we are on the page:

 /blog/myblog-1/page/2

the link to page 3 is:

 /blog/myblog-1/page/3

So we need to give /blog/our-blog-1 as source url of pager.

Previously in this instance, since 4faed0b7 the page 3 url
in this scenario would erroneously be:

 /blog/myblog-1/page/2/page/3

opw-688681

addons/website_blog/controllers/main.py

@@ -127,7 +127,7 @@ class WebsiteBlog(http.Controller):
         blog_posts = blog_post_obj.browse(cr, uid, blog_post_ids, context=context)
 
         pager = request.website.pager(
-            url=request.httprequest.path,
+            url=request.httprequest.path.partition('/page/')[0],
             total=len(blog_posts),
             page=page,
             step=self._blog_post_per_page,