[MacPorts] #62871: boost: default to python39 variant

[MacPorts]

#62871: boost: default to python39 variant
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 Reporter:  mohd-akram   |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  ports        |    Version:
 Keywords:               |       Port:  boost
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Ticket URL: <https://trac.macports.org/ticket/62871>
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