layouts: Fix a few outdated .font-italic uses

In Bootstrap v5 the font utility classes were renamed.

layouts/_default/home.html

@@ -34,7 +34,7 @@
 
   <div class="row">
     <div class="col-md-8">
-      <h3 class="pb-4 mb-4 font-italic border-bottom">
+      <h3 class="pb-4 mb-4 fst-italic border-bottom">
         From the Firehose
       </h3>
 

layouts/partials/featured.html

@@ -5,7 +5,7 @@
 {{ if eq $index 0 }}
   <div class="p-4 p-md-5 mb-4 text-white rounded bg-dark">
     <div class="col-md-6 px-0">
-      <h1 class="display-4 font-italic">{{ .Title }}</h1>
+      <h1 class="display-4 fst-italic">{{ .Title }}</h1>
       <p class="lead my-3">{{ substr .Description 0 110 }}</p>
       <p class="lead mb-0"><a href="{{ .Permalink }}" class="text-white fw-bold">Continue reading...</a></p>
     </div>

layouts/partials/recent.html

@@ -1,5 +1,5 @@
 	<div class="p-4">
-		<h4 class="font-italic">Archives</h4>
+		<h4 class="fst-italic">Archives</h4>
 		<ol class="list-unstyled mb-0">
 {{ $num_recent_posts := (index .Site.Params.sidebar "num_recent_posts" | default 5) }}
 {{ range first $num_recent_posts (where .Site.RegularPages "Section" "in" .Site.Params.mainSections) }}

layouts/partials/sidebar.html

@@ -1,7 +1,7 @@
 <div class="col-md-4">
   {{ if and (.Site.Params.sidebar) (isset .Site.Params.sidebar "about") }}
 	<div class="p-4 mb-3 bg-light rounded">
-		<h4 class="font-italic">About</h4>
+		<h4 class="fst-italic">About</h4>
     <p class="mb-0">{{ .Site.Params.sidebar.about | markdownify }}</p>
 	</div>
   {{ end }}
@@ -12,7 +12,7 @@
 
   {{ with .Site.Menus.sidebar }}
 	<div class="p-4">
-		<h4 class="font-italic">Elsewhere</h4>
+		<h4 class="fst-italic">Elsewhere</h4>
 		<ol class="list-unstyled">
       {{ range . }}
       <li><a href="{{ .URL | absURL }}">{{ .Name }}</a></li>