Use release helper from libosmocore

See
https://osmocom.org/projects/cellular-infrastructure/wiki/Make_a_new_release
for details.

Change-Id: Icdcb388ad22b0c009dac7968408d1e2504c838c1
Related: OS#1861
diff --git a/debian/changelog b/debian/changelog
index 17a0a36..357cc01 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,4 +1,4 @@
-openggsn (0.94) UNRELEASED; urgency=medium
+openggsn (0.94.0) UNRELEASED; urgency=medium
 
   [ Holger Hans Peter Freyther ]
   * Bump version to ease upgrading from Debian SID.