[sociald] Force timestamps to be upsynced with milliseconds. Contributes to JB#19086
[sociald] Force timestamps to be upsynced with milliseconds. Contributes to JB#19086

This commit ensures that when contact update timestamps are
synchronized to Google that they are explicitly formatted in to
include millisecond information, which Google requires.

Contributes to JB#19086

rainisto/buteo-sync-plugins-social,rainisto/buteo-sync-plugins-social