net-im/py-sleekxmpp: Update to 1.3.3

Changelog:
https://github.com/fritzy/SleekXMPP/releases/tag/sleek-1.3.3

Additional port changes:

• Changed to DISTVERSION
• Changed MASTER_SITES to CHEESESHOP
• Added LICENSE_FILE
• Added RUN_DEPENDS according to setup.py
• Added NO_ARCH=yes

Reported by: portscout
Approved by: tcberner (mentor, implicit)