[FIX] website_blog: display all the blog posts when filtered

Before this commit, following these steps:
- Go to /blog
- Activate the option Customize > Top banner - Name / Latest Post
- Disable the option Customize > Full Width Cover
- Click on the "guides" tag of the "Buying A Telescope" blog

No blog is displayed. This was because the top banner post is not shown
when the posts are filtered. Basically, once filtered, a blog post was
always missing.

Related to opw-2882492

X-original-commit: ee2f778abb8b7a6e221e05361bc7b964593d1123
Part-of: odoo/odoo#104639

addons/website_blog/controllers/main.py

@@ -113,7 +113,7 @@ class WebsiteBlog(http.Controller):
         # if blog, we show blog title, if use_cover and not fullwidth_cover we need pager + latest always
         offset = (page - 1) * self._blog_post_per_page
         if not blog:
-            if use_cover and not fullwidth_cover:
+            if use_cover and not fullwidth_cover and not tags and not date_begin and not date_end:
                 offset += 1
 
         options = self._get_blog_post_search_options(