[libsecret] Fix nullable in secret_collection_for_alias_*

[Niels De Graef <nielsdg src gnome org>]

commit 921f5f0d2eda9f87c6a6af234d068addb5d749f1
Author: Julian Schmidhuber <gitlab schmiddi anonaddy com>
Date:   Thu Sep 8 15:24:35 2022 +0200

    Fix nullable in secret_collection_for_alias_*

 libsecret/secret-collection.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/libsecret/secret-collection.c b/libsecret/secret-collection.c
index 0ce32a5..635e173 100644
--- a/libsecret/secret-collection.c
+++ b/libsecret/secret-collection.c
@@ -2166,7 +2166,7 @@ secret_collection_for_alias (SecretService *service,
  * Finish an asynchronous operation to lookup which collection is assigned
  * to an alias.
  *
- * Returns: (transfer full): the collection, or %NULL if none assigned to the alias
+ * Returns: (transfer full) (nullable): the collection, or %NULL if none assigned to the alias
  */
 SecretCollection *
 secret_collection_for_alias_finish (GAsyncResult *result,
@@ -2202,7 +2202,7 @@ secret_collection_for_alias_finish (GAsyncResult *result,
  *
  * This method may block and should not be used in user interface threads.
  *
- * Returns: (transfer full): the collection, or %NULL if none assigned to the alias
+ * Returns: (transfer full) (nullable): the collection, or %NULL if none assigned to the alias
  */
 SecretCollection *
 secret_collection_for_alias_sync (SecretService *service,