[MacPorts] #69723: osl: Add and default to python312 variant

[MacPorts]

#69723: osl: Add and default to python312 variant
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 Reporter:  ryandesign  |      Owner:  jasonliu--
     Type:  defect      |     Status:  assigned
 Priority:  Normal      |  Milestone:
Component:  ports       |    Version:
 Keywords:              |       Port:  osl
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Ticket URL: <https://trac.macports.org/ticket/69723>
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