build: automatic update of test-app

updates image nginx tag '1.21.0' to '1.23.1'

helm-guestbook/.argocd-source-test-app.yaml

@@ -0,0 +1,8 @@
+helm:
+  parameters:
+  - name: image.name
+    value: nginx
+    forcestring: true
+  - name: image.tag
+    value: 1.23.1
+    forcestring: true