add ITP bug number

Author: bbonev

debian/changelog

@@ -1,5 +1,5 @@
 bpfmon (2.46-1) unstable; urgency=medium
 
-  * Initial release (Closes: #-1)
+  * Initial release (Closes: #969931)
 
  -- Boian Bonev <bbonev@ipacct.com>  Wed, 12 Aug 2020 18:55:16 +0000