Update watch file format version to 4.

Changes-By: lintian-brush
Fixes: lintian: older-debian-watch-file-standard
See-also: https://lintian.debian.org/tags/older-debian-watch-file-standard.html

debian/changelog

@@ -11,6 +11,7 @@ ruby-net-ssh-gateway (2.0.0-2) UNRELEASED; urgency=medium
   * Use canonical URL in Vcs-Git.
   * Set upstream metadata fields: Bug-Database, Bug-Submit, Repository,
     Repository-Browse.
+  * Update watch file format version to 4.
 
  -- Utkarsh Gupta <guptautkarsh2102@gmail.com>  Tue, 13 Aug 2019 06:11:11 +0530
 

debian/watch

-version=3
+version=4
 http://pkg-ruby-extras.alioth.debian.org/cgi-bin/gemwatch/net-ssh-gateway .*/net-ssh-gateway-(.*).tar.gz