Set upstream metadata fields: Security-Contact.

Changes-By: lintian-brush

debian/changelog

@@ -1,6 +1,7 @@
 dulwich (0.20.25-2) UNRELEASED; urgency=medium
 
   * Bump debhelper from old 12 to 13.
+  * Set upstream metadata fields: Security-Contact.
 
  -- Debian Janitor <janitor@jelmer.uk>  Sun, 19 Sep 2021 14:38:03 -0000
 

debian/upstream/metadata

@@ -2,3 +2,4 @@ Repository: https://github.com/dulwich/dulwich.git
 Repository-Browse: https://github.com/dulwich/dulwich
 Bug-Database: https://github.com/dulwich/dulwich/issues
 Bug-Submit: https://github.com/dulwich/dulwich/issues/new
+Security-Contact: https://github.com/dulwich/dulwich/tree/HEAD/SECURITY.md