Allow topic "content metadata" to wrap

Now that a bit more info (link publication dates) is being shown inside
the topic content metadata sometimes, white-space: nowrap probably isn't
a very good idea and has a chance of causing issues on mobile. Just
letting it wrap should be fine most of the time, though it could look a
little strange when it wraps in the middle of a word count or date.

tildes/scss/modules/_topic.scss

@@ -81,10 +81,6 @@
   align-items: center;
 }
 
-.topic-content-metadata {
-  white-space: nowrap;
-}
-
 .topic-group {
   margin-right: 0.4rem;
 }