meson: ldap-config: add missing cereal dep

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Iff963fc90cc480761da44a2da6a6f6702b450d0a
diff --git a/phosphor-ldap-config/meson.build b/phosphor-ldap-config/meson.build
index 4331483..c647008 100644
--- a/phosphor-ldap-config/meson.build
+++ b/phosphor-ldap-config/meson.build
@@ -1,4 +1,5 @@
 phosphor_ldap_conf_deps = [
+    cereal_dep,
     phosphor_dbus_interfaces_dep,
     phosphor_logging_dep,
     sdbusplus_dep,