Log Message:
py-objgraph: updated to 3.5.0

3.5.0:
Do not require mock for the test suite on Python 3; use unittest.mock instead.
100% test coverage for each version of Python rather than combined, using \ 
coverage-python-version.
Add the optional extra_node_attrs parameter to show_backrefs and show_backrefs
Fix IPython/Jupyter inline graph support code that would kick in even if you \ 
explicitly passed a filename=’foo.png’ argument to show_refs/show_backrefs. \ 
See issue 47.
Add support for Python 3.8.
Drop support for Python 3.5.