Update microk8s.nsi (#2587)

Actually bump version number

Author: joedborg

installer/windows/microk8s.nsi

@@ -4,7 +4,7 @@
 !include "Sections.nsh"
 
 !define PRODUCT_NAME "MicroK8s"
-!define PRODUCT_VERSION "2.1.0"
+!define PRODUCT_VERSION "2.2.0"
 !define PRODUCT_PUBLISHER "Canonical"
 !define MUI_ICON ".\microk8s.ico"
 !define MUI_HEADERIMAGE