[geary/mjog/fix-timezone-deprecation] engine: Use nullable version of GLib.Timezone.identifier

[Michael Gratton <mjog src gnome org>]

commit bfa0c8fc8fb4eeb24a1e1c0bea6ad870ce224d04
Author: Michael Gratton <mike vee net>
Date:   Tue Apr 6 14:09:14 2021 +1000

    engine: Use nullable version of GLib.Timezone.identifier

 src/engine/imap/message/imap-internal-date.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/engine/imap/message/imap-internal-date.vala b/src/engine/imap/message/imap-internal-date.vala
index d2aa96e4b..53b883f94 100644
--- a/src/engine/imap/message/imap-internal-date.vala
+++ b/src/engine/imap/message/imap-internal-date.vala
@@ -82,7 +82,7 @@ public class Geary.Imap.InternalDate : Geary.MessageData.AbstractMessageData, Ge
         GLib.TimeZone? timezone = null;
         if (tz[0] != '\0') {
             string tz_string = (string) tz;
-            timezone = new GLib.TimeZone.identifier(tz_string);
+            timezone = GLib.TimeZone.new_from_identifier(tz_string);
             if (timezone == null) {
                 warning("Invalid INTERNALDATE timezone \"%s\"", tz_string);
             }