[gnome-contacts] Fix some dynamic cast warnings

[Niels De Graef <nielsdg src gnome org>]

commit a978bfdd463e6331740551b80d5d66e6e1486437
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Fri Jun 5 10:06:40 2020 +0200

    Fix some dynamic cast warnings

 src/contacts-accounts-list.vala    | 3 ++-
 src/contacts-addressbook-list.vala | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/src/contacts-accounts-list.vala b/src/contacts-accounts-list.vala
index 8c0f0be..8f0fdfb 100644
--- a/src/contacts-accounts-list.vala
+++ b/src/contacts-accounts-list.vala
@@ -76,7 +76,8 @@ public class Contacts.AccountsList : ListBox {
         local_store = persona_store;
         continue;
       }
-      var source = (persona_store as Edsf.PersonaStore).source;
+
+      var source = ((Edsf.PersonaStore) persona_store).source;
       var parent_source = eds_source_registry.ref_source (source.parent);
       var provider_name = Contacts.Utils.format_persona_store_name (persona_store);
 
diff --git a/src/contacts-addressbook-list.vala b/src/contacts-addressbook-list.vala
index c59a30a..693863e 100644
--- a/src/contacts-addressbook-list.vala
+++ b/src/contacts-addressbook-list.vala
@@ -83,7 +83,7 @@ public class Contacts.AddressbookList : ListBox {
         local_store = persona_store;
         continue;
       }
-      var source = (persona_store as Edsf.PersonaStore).source;
+      var source = ((Edsf.PersonaStore) persona_store).source;
       var parent_source = eds_source_registry.ref_source (source.parent);
       var provider_name = Utils.format_persona_store_name (persona_store);