add 2.7.6 version in upgrade process

www/install/sql/centreon/Update-DB-2.7.5_to_2.7.6.sql

+ALTER TABLE `contact` CHANGE `contact_location` `contact_location` int(11) DEFAULT NULL;
+
+-- Change version of Centreon
+UPDATE `informations` SET `value` = '2.7.6' WHERE CONVERT( `informations`.`key` USING utf8 )  = 'version' AND CONVERT ( `informations`.`value` USING utf8 ) = '2.7.5' LIMIT 1;