devel/py-decorator: Update to 4.0.9

• Update PORTVERSION and distinfo checksum (4.0.9)
• Add LICENSE_FILE
• Add test target
• Enable NO_ARCH (architecture independent)
• Update pkg-descr WWW: URL to match setup.py:url=

This change fixes www/py-praw after r410501 [1], which depends on this
version (4.0.9) as a minimum.

Maintainer email address is currently experience MX lookup failure:

Technical details of temporary failure:
DNS Error: 132075314 DNS type 'mx' lookup of wizard.volgograd.ru
responded with code SERVFAIL

[1] https://svnweb.freebsd.org/changeset/ports/410501

PR: 207894
Approved by: portmgr (maintainer email failure)
Differential Revision: D5606