[MacPorts] #56414: mlt: upgrade to v6.6.0

[MacPorts]

#56414: mlt: upgrade to v6.6.0
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  Reporter:  ddennedy  |      Owner:  (none)
      Type:  update    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:
Resolution:            |   Keywords:  maintainer haspatch
      Port:  mlt       |
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Comment (by pmetzger):

 ddennedy: could you re-submit this as a GitHub Pull Request? It is likely
 to be acted on faster if you do.

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Ticket URL: <https://trac.macports.org/ticket/56414#comment:5>
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