remove trailing whitespace in phx.gen.html index

Accidentally added in #5820

Author: SteffenDE

priv/templates/phx.gen.html/index.html.heex

@@ -1,7 +1,7 @@
 <.header>
   Listing <%= schema.human_plural %>
   <:actions>
-    <.button phx-click={JS.dispatch("click", to: {:inner, "a"})}> 
+    <.button phx-click={JS.dispatch("click", to: {:inner, "a"})}>
       <.link href={~p"<%= schema.route_prefix %>/new"}>
         New <%= schema.human_singular %>
       </.link>