tests: Make sure we specify guint64 with g_object_set arguments
tests: Make sure we specify guint64 with g_object_set arguments

Avoids crashers on 32bit machines

pitivi/gst-editing-services,cfoch/ges,volodymyrrudyi/gst-editing-services,cfoch/gst-editing-services,freesteph/gst-editing-services,cfoch/gst-editing-services,cfoch/ges,pitivi/gst-editing-services,ahmedammar/platform_external_gst_editing_services,cfoch/ges,pitivi/gst-editing-services,MathieuDuponchelle/PitiviGes,luisbg/gst-editing-services,cfoch/ges,volodymyrrudyi/gst-editing-services,ahmedammar/platform_external_gst_editing_services,pitivi/gst-editing-services,freesteph/gst-editing-services,MathieuDuponchelle/PitiviGes,cfoch/gst-editing-services,luisbg/gst-editing-services,cfoch/gst-editing-services,MathieuDuponchelle/PitiviGes,volodymyrrudyi/gst-editing-services,freesteph/gst-editing-services,MathieuDuponchelle/PitiviGes