[MacPorts] #51310: ImageMagick: update to 7.x

[MacPorts]

#51310: ImageMagick: update to 7.x
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  Reporter:  mopihopi     |      Owner:  ryandesign
      Type:  update       |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:
      Port:  ImageMagick  |
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Comment (by Dave-Allured):

 I have started a new port imagemagick7 to coexist with the current
 ImageMagick version 6.  This is supposed to leave IM6 and IM6 dependants
 untouched, like I suggested earlier.  Help wanted for testing, checking
 for conflicts, and refinement.  PR https://github.com/macports/macports-
 ports/pull/21692.  If you want IM7, please try out this port on your own
 system.

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Ticket URL: <https://trac.macports.org/ticket/51310#comment:81>
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