py-rdflib: updated to 5.0.0

RELEASE 5.0.0

5.0.0 is a major stable release and is the last release to support Python 2 & 3.4. 5.0.0 is mostly backwards-
compatible with 4.2.2 and is intended for long-term, bug fix only support.

General Bugs Fixed:
  * Fix n3 parser exponent syntax of floats with leading dot.
  * FIX: Change is comparison to == for tuple
  * fix: Added _parseBoolean function to enforce correct Lexical-to-value mapping

Enhanced Features:
  * Issue 1003

SPARQL Fixes:
  * CONSTRUCT resolve with initBindings

Documentation Fixes:
  * DOC: Use sphinxcontrib-apidoc and various cleanups
  * Update copyright year in docs conf.py
  * slightly improved styling, small index text changes

(adam)