style: correct coding style with rubocop linter

app/mailers/ticket_mailer.rb

@@ -1,21 +1,21 @@
 class TicketMailer < ApplicationMailer
-  default from: 'notifications@aperonight.com'
+  default from: "notifications@aperonight.com"
 
   def purchase_confirmation(ticket)
     @ticket = ticket
     @user = ticket.user
     @event = ticket.event
-    
+
     # Generate PDF attachment
     pdf = @ticket.to_pdf
     attachments["ticket-#{@event.name.parameterize}-#{@ticket.qr_code[0..7]}.pdf"] = {
-      mime_type: 'application/pdf',
+      mime_type: "application/pdf",
       content: pdf
     }
-    
+
     mail(
       to: @user.email,
       subject: "Confirmation d'achat - #{@event.name}"
     )
   end
-end
+end