apps/do: oauth for vikunja-test

apps/do/vikunja-secrets/vikunja-test-oauth-secret.yaml

+---
+apiVersion: secretgenerator.mittwald.de/v1alpha1
+kind: StringSecret
+metadata:
+  name: stackspin-vikunja-test-oauth-variables
+  namespace: flux-system
+spec:
+  data:
+    client_id: vikunja-test
+  fields:
+  - fieldName: client_secret
+    length: "32"

apps/do/vikunja-test/vikunja-oauth-client.yaml

@@ -15,7 +15,7 @@ spec:
     - id_token
     - code
   scope: "openid profile email stackspin_roles"
-  secretName: stackspin-vikunja-oauth-variables
+  secretName: stackspin-vikunja-test-oauth-variables
   redirectUris:
     - https://test.${vikunja_domain}/auth/openid/stackspin
   tokenEndpointAuthMethod: client_secret_post