[MacPorts] #51512: meld: bump version to 3.16.0

[MacPorts]

#51512: meld: bump version to 3.16.0
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  Reporter:  josephsacco  |      Owner:  macports-tickets@…
      Type:  update       |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:  haspatch
      Port:  meld         |
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Comment (by raimue):

 The `post-activate` phase must be kept to update the various database
 indexes for which new files were installed.

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Ticket URL: <https://trac.macports.org/ticket/51512#comment:6>
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