set secure attribute on cookies

request-tracker/templates/RT_SiteConfig.d/50-debconf.pm.j2

@@ -17,6 +17,7 @@ Set($CanonicalizeURLsInFeeds, 1);
 Set($WebPort, '443');
 Set($WebPath , "");
 Set($WebBaseURL , 'https://{{rt_webdomain}}');
+Set($WebSecureCookies, 1);
 
 ### Addresses
 Set($CorrespondAddress, '{{rt_correspondaddress}}');