Implement Sync for DateTime

It's immutable.

Gir_Gst.toml

@@ -69,6 +69,7 @@ generate = [
     "Gst.ParseFlags",
     "Gst.TaskState",
     "Gst.PluginDependencyFlags",
+    "Gst.DateTime",
 ]
 
 manual = [
@@ -211,11 +212,6 @@ name = "Gst.TocEntry"
 status = "manual"
 ref_mode = "ref"
 
-[[object]]
-name = "Gst.DateTime"
-status = "generate"
-concurrency = "send"
-
 [[object]]
 name = "Gst.Clock"
 status = "generate"

gstreamer/src/auto/date_time.rs

@@ -189,3 +189,4 @@ impl DateTime {
 }
 
 unsafe impl Send for DateTime {}
+unsafe impl Sync for DateTime {}