Subscriptions and notifications for namespaces, tasks and lists (#786)

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/786
Co-authored-by: konrad <konrad@kola-entertainments.de>
Co-committed-by: konrad <konrad@kola-entertainments.de>

pkg/models/unit_tests.go

@@ -59,6 +59,7 @@ func SetupTests() {
 		"users_namespace",
 		"buckets",
 		"saved_filters",
+		"subscriptions",
 	)
 	if err != nil {
 		log.Fatal(err)