[bug] Fix issue with Slime show template

These lines were being interpreted by the Slime
preprocessor as lines using Embedded engines due to the
fact that they were a single word line ending with a colon.

This fix will manually tag these lines with the "Verbatim text"
line indicator (`|`) so that the preprocessor knows how to handle
them.

priv/templates/slime/phx.gen.html/show.html.slime

@@ -10,7 +10,7 @@ section#torch-header-and-content
     <%= for {k, _} <- schema.attrs do %>
       li
         .torch-show-label
-          <%= Phoenix.Naming.humanize(Atom.to_string(k)) %>:
+          | <%= Phoenix.Naming.humanize(Atom.to_string(k)) %>:
         .torch-show-data
           = @<%= schema.singular %>.<%= k %>
-    <% end %>
+    <% end %>