.......... [ZBXNEXT-826] updated release date and version [1.8.21]

git-svn-id: svn://svn.zabbix.com/trunk@48913 f4e7fd02-d210-4e34-a1e0-d4093fb66cc2
.......... [ZBXNEXT-826] updated release date and version [2.0.13]

git-svn-id: svn://svn.zabbix.com/trunk@48914 f4e7fd02-d210-4e34-a1e0-d4093fb66cc2