Use realIP

Code was copied from https://github.com/go-chi/chi/blob/master/middleware/realip.go

cmd/web/handlers.go

@@ -277,7 +277,7 @@ func (app *application) createVotesHandleKnownVotersElection(w http.ResponseWrit
 }
 
 func (app *application) createVotesHandleUnknownVotersElection(w http.ResponseWriter, r *http.Request, election *models.Election) (string, error) {
-	voterIdentity := r.RemoteAddr
+	voterIdentity := realIP(r)
 
 	voterExists, err := app.voters.Exists(voterIdentity, election.ID)
 	if err != nil {