Log Message:
libsecret: update to 0.18.7.

0.18.7
 * Migrate from intltool to gettext [!2]
 * Fix uninitialized memory returned by secret_item_get_schema_name() [#15]
 * secret-session: Avoid double-free in service_encode_plain_secret()
 * Port tap script to Python 3 [!4]
 * Build and test fixes [#734630]
 * Updated translations