[MacPorts] #53794: Update ncarg to 6.4.0

[MacPorts]

#53794: Update ncarg to 6.4.0
--------------------------+-------------------
 Reporter:  Dave-Allured  |      Owner:
     Type:  update        |     Status:  new
 Priority:  Normal        |  Milestone:
Component:  ports         |    Version:
 Keywords:                |       Port:  ncarg
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 Please update to Ncarg version 6.4.0 (NCAR Graphics with NCL).  Thank you.

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Ticket URL: <https://trac.macports.org/ticket/53794>
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