Add use .Site.RegularPages for pagination

Hugo v0.57.0 changed the behavior of the page variables. This caused
some broken theme demos. This fix uses .Site.RegularPages to get former,
expected list of pages back.

layouts/partials/post-list.html

@@ -1,7 +1,7 @@
 <main>
     <div id="home">
         <ul class="posts">
-        {{ $paginator := .Paginate (where .Data.Pages.ByDate.Reverse "Type" "post") }}
+        {{ $paginator := .Paginate (where .Site.RegularPages.ByDate.Reverse "Type" "post") }}
         {{ range $paginator.Pages }}
             <li itemscope itemtype="//schema.org/BlogPosting">
                 <a href="{{ .Permalink }}" itemprop="url">