[MacPorts] #62956: Update libxml2 to 2.9.12

[MacPorts]

#62956: Update libxml2 to 2.9.12
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 Reporter:  ghosthound  |      Owner:  ghosthound
     Type:  defect      |     Status:  assigned
 Priority:  Normal      |  Milestone:
Component:  ports       |    Version:
 Keywords:              |       Port:  libxml2
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 Update libxml2 to 2.9.12

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Ticket URL: <https://trac.macports.org/ticket/62956>
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