Add release dates to changelog.
Add release dates to changelog.

GhassenRjab/wekan,libreboard/libreboard,oliver4u/WEKAN_runpartner,libreboard/libreboard,johnleeming/wekan,nztqa/wekan,mario-orlicky/wekan,Serubin/wekan,jtickle/wekan,wekan/wekan,ddanssaert/wekan,oliver4u/WEKAN_runpartner,oliver4u/sap-wekan,johnleeming/wekan,mario-orlicky/wekan,GhassenRjab/wekan,wekan/wekan,nztqa/wekan,oliver4u/WEKAN_runpartner,oliver4u/sap-wekan,jtickle/wekan,GhassenRjab/wekan,nztqa/wekan,Serubin/wekan,johnleeming/wekan,wekan/wekan,wekan/wekan,jtickle/wekan,johnleeming/wekan,ddanssaert/wekan,wekan/wekan,Serubin/wekan,oliver4u/sap-wekan,ddanssaert/wekan,mario-orlicky/wekan