[MacPorts] #56072: update py-pyqtgraph and add py36

[MacPorts]

#56072: update py-pyqtgraph and add py36
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 Reporter:  jjstickel  |      Owner:
     Type:  defect     |     Status:  new
 Priority:  Normal     |  Milestone:
Component:  ports      |    Version:
 Keywords:  py36       |       Port:  py-pyqtgraph
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 See attached patch to the portfile.

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Ticket URL: <https://trac.macports.org/ticket/56072>
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