Add backwards compatibility for twitter share button

Author: zanseb

layouts/partials/share_icons.html

@@ -14,7 +14,7 @@
 {{- with $ShareButtons }}{{ $custom = true }}{{ end }}
 
 <div class="share-buttons">
-    {{- if (cond ($custom) (in $ShareButtons "x") (true)) }}
+    {{- if (cond ($custom) (in $ShareButtons "x") (true)) | or (cond ($custom) (in $ShareButtons "twitter") (true)) }}
     <a target="_blank" rel="noopener noreferrer" aria-label="share {{ $title | plainify }} on x"
         href="https://x.com/intent/tweet/?text={{ $title }}&amp;url={{ $pageurl }}&amp;hashtags={{- $.Scratch.Get "tags" -}}">
         <svg version="1.1" viewBox="0 0 512 512" xml:space="preserve" height="30px" width="30px" fill="currentColor">