Retry release notes after a few seconds

I have been seeing the error "unable to detect release" due
to a timing issue between the webhook and GitHub's API
updating current releases.

This enables a single retry and I'll monitor it from there.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

derek.yml

@@ -3,9 +3,9 @@ provider:
   gateway: http://127.0.0.1:8080
 
 functions:
-  derek-0110:
+  derek-0113:
     handler: ./
-    image: ghcr.io/alexellis/derek:0.11.0
+    image: ghcr.io/alexellis/derek:0.11.3
     lang: dockerfile
     environment:
       debug: true

main.go

@@ -10,6 +10,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"time"
 
 	"github.com/google/go-github/github"
 
@@ -238,6 +239,15 @@ func handleEvent(eventType string, bytesIn []byte, config config.Config) error {
 
 				handler := handler.NewReleaseHandler(config, int(req.Installation.GetID()))
 				err = handler.Handle(req)
+				// retry once - with a 5 second delay
+				if err != nil && err.Error() == "unable to detect current release, retry webhook after a few seconds" {
+					time.Sleep(time.Second * 5)
+					err = handler.Handle(req)
+					if err != nil {
+						err = fmt.Errorf("got an error, then retried after 5 seconds: %w", err)
+					}
+
+				}
 			}
 			return err
 		}