Use secure copyright file specification URI.

Fixes: lintian: insecure-copyright-format-uri
See-also: https://lintian.debian.org/tags/insecure-copyright-format-uri.html

debian/changelog

 node-es6-set (0.1.5-2) UNRELEASED; urgency=medium
 
   * Trim trailing whitespace.
+  * Use secure copyright file specification URI.
 
  -- Debian Janitor <janitor@jelmer.uk>  Fri, 24 Apr 2020 07:18:18 +0000
 

debian/copyright

-Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
 Upstream-Name: es6-set
 Upstream-Contact: https://github.com/medikoo/es6-set/issues
 Source: https://github.com/medikoo/es6-set#readme