Use debhelper-compat and update to compat level 13

Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>

debian/compat

-9

debian/control

@@ -6,7 +6,7 @@ Uploaders:
  Varun Hiremath <varun@debian.org>,
  Andrew Ross <ubuntu@rossfamily.co.uk>
 Build-Depends:
- debhelper (>= 9),
+ debhelper-compat (= 13),
  default-jdk,
  javahelper (>= 0.40ubuntu1),
  libnb-org-openide-util-java (>= 8.1),