Increase processing timeout (#40)

Calculating diffs on promotion pull requests like [1] fails since the
context is timing out and processing is aborted. This is evident from
logs.

    Error getting manifests for app ..., revision ...:
	rpc error: code = DeadlineExceeded desc = context deadline exceeded"
    Error generating diff for component ...:
	rpc error: code = DeadlineExceeded desc = context deadline exceeded"
    Handling of PR event failed: err=getting diff information:
	rpc error: code = DeadlineExceeded desc = context deadline exceeded\n" ...

Increasing the timeout is a short-term fix to mitigate the issue and
allow users to get the diff while additional investigation is done to
figure out how we can address this better long-term.

[1] commercetools/k8s-gitops#998

internal/pkg/githubapi/github.go

@@ -367,7 +367,7 @@ func ReciveWebhook(r *http.Request, mainGhClientCache *lru.Cache[string, GhClien
 func handleEvent(eventPayloadInterface interface{}, mainGhClientCache *lru.Cache[string, GhClientPair], prApproverGhClientCache *lru.Cache[string, GhClientPair], r *http.Request, payload []byte) {
 	// We don't use the request context as it might have a short deadline and we don't want to stop event handling based on that
 	// But we do want to stop the event handling after a certain point, so:
-	ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
 	defer cancel()
 	var mainGithubClientPair GhClientPair
 	var approverGithubClientPair GhClientPair