Removing updateserver tag since no actual updateserver is defined

Having the <updateservers> tag in your install file breaks the updater. The problem is that it produces an invalid database entry and the updater doesn't find the updateserver.

Either add an updateserver or remove these tags.
Of course adding an updateserver would be the better solution :-)
Akeeba Release System from https://www.akeebabackup.com/products/akeeba-release-system.html is really helpful here.