website: blog: Refer to the localized URL in breadcrumbs.

Fixes <https://issues.guix.gnu.org/63975>.
Reported by Maxime Devos <maximedevos@telenet.be>.

* website/apps/blog/utils.scm (post-url-path): Append a slash to
the URL, so the guix-url procedure will treat it as a web page
and localize it.

website/apps/blog/utils.scm

@@ -1,5 +1,6 @@
 ;;; GNU Guix web site
 ;;; Copyright © 2016, 2017, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2023 Florian Pelz <pelzflorian@pelzflorian.de>
 ;;;
 ;;; This file is part of the GNU Guix web site.
 ;;;
@@ -54,9 +55,12 @@
 
    POST (<post>)
      A post object as defined in (haunt post) module."
+  ;; Note: End the path with a slash so 'localized-root-path' down the road
+  ;; prepends the language tag.
   (url-path-join "blog"
 		 (date->string (post-date post) "~Y")
-		 (post-slug post)))
+                 (post-slug post)
+                 ""))
 
 
 (define (posts/latest posts n)