myspace: always consider regie id as a string (#39973)

auquotidien/modules/myspace.py

@@ -50,7 +50,7 @@ class MyInvoicesDirectory(Directory):
         invoices = []
         invoices.extend(Invoice.get_with_indexed_value(
             str('user_id'), str(user.id)))
-        invoices.sort(key=lambda x: (x.regie_id, -x.date.toordinal()))
+        invoices.sort(key=lambda x: (str(x.regie_id), -x.date.toordinal()))
 
         last_regie_id = None
         unpaid = False