Fix #4405: Post version table css doesn't keep ratio at smaller resolutions.

Bug: extremely long sources cause the Tags column to become extremely
wide. Caused by the source link not having the word-break property set.

Fix: use post_source_tag, which lets the `a[rel=external] { word-break: break-word; }`
rule take effect.

Example: https://danbooru.donmai.us/post_versions?search%5Bpost_id%5D=3809742

app/views/posts/partials/show/_information.html.erb

@@ -22,7 +22,7 @@
       (<span itemprop="width"><%= post.image_width %></span>x<span itemprop="height"><%= post.image_height %></span>)
     <% end %>
   </li>
-  <li id="post-info-source">Source: <%= post_source_tag(post) %></li>
+  <li id="post-info-source">Source: <%= post_source_tag(post.source, post.normalized_source) %></li>
   <li id="post-info-rating">Rating: <%= post.pretty_rating %></li>
   <li id="post-info-score">Score: <span id="score-for-post-<%= post.id %>"><%= post.score %></span>
     <% if policy(PostVote).create? %>