Update to new interpolation syntax

Includes a fix to a brittle test that failed due to changes in the
number of linebreaks.

lib/music_library_web/components/layouts/app.html.heex

@@ -4,28 +4,28 @@
       <div class="flex">
         <div class="flex space-x-4 md:space-x-8">
           <.link navigate={~p"/"} class={section_link_classes(assigns[:nav_section], :stats)}>
-            <%= gettext("Stats") %>
+            {gettext("Stats")}
           </.link>
           <.link
             navigate={~p"/collection"}
             class={section_link_classes(assigns[:nav_section], :records)}
           >
-            <%= gettext("Collection") %>
+            {gettext("Collection")}
           </.link>
           <.link
             navigate={~p"/wishlist"}
             class={section_link_classes(assigns[:nav_section], :wishlist)}
           >
-            <%= gettext("Wishlist") %>
+            {gettext("Wishlist")}
           </.link>
         </div>
       </div>
       <div class="flex space-x-8">
         <a class={["max-sm:hidden" | nav_link_classes()]} } href={~p"/dev/dashboard"}>
-          <%= gettext("Dev dashboard") %>
+          {gettext("Dev dashboard")}
         </a>
         <a class={nav_link_classes()} } href={~p"/login"}>
-          <%= gettext("Logout") %>
+          {gettext("Logout")}
         </a>
       </div>
     </div>
@@ -34,6 +34,6 @@
 <main class="px-4 py-4 max-sm:pb-20 sm:px-6 lg:px-8">
   <div class="mx-auto max-w-screen-xl">
     <.flash_group flash={@flash} />
-    <%= @inner_content %>
+    {@inner_content}
   </div>
 </main>