[MacPorts] #58335: Update darktable to 2.6.2

[MacPorts]

#58335: Update darktable to 2.6.2
-------------------------+-------------------------------------------------
 Reporter:  luzpaz       |      Owner:  (none)
     Type:  update       |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  ports        |    Version:
 Keywords:               |       Port:  https://github.com/macports
                         |  /macports-ports/blob/master/graphics/darktable
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 Changelog: https://www.darktable.org/2019/03/darktable-262-released/

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Ticket URL: <https://trac.macports.org/ticket/58335>
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