Log Message:
py-graphviz: updated to 0.9

Version 0.9
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Use sys.stderr to write stderr output from rendering process to stderr (instead
of file descriptor inhertiance). Ensures stderr is passed in special
enviroments such as IDLE.

Suppress rendering process stdout in render().

Make quiet=True also suppress stderr on success of render() and pipe() (zero
exit-status).

Include stderr from rendering process in CalledProcessError exception.