fix: drop ! from get_attendee_with_badge_count_by_username function

lib/safira/accounts/accounts.ex

@@ -110,7 +110,7 @@ defmodule Safira.Accounts do
     end
   end
 
-  def get_attendee_with_badge_count_by_username!(username) do
+  def get_attendee_with_badge_count_by_username(username) do
     case get_attendee_by_username!(username) do
       nil ->
         nil

lib/safira_web/controllers/attendee_controller.ex

@@ -42,7 +42,7 @@ defmodule SafiraWeb.AttendeeController do
 
   def show(conn, _) when is_map_key(conn.query_params, "username") do
     username = conn.query_params["username"]
-    attendee = Accounts.get_attendee_with_badge_count_by_username!(username)
+    attendee = Accounts.get_attendee_with_badge_count_by_username(username)
 
     cond do
       is_nil(attendee) ->