[MacPorts] #69741: libmamba: Remove ghc-filesystem dependency

[MacPorts]

#69741: libmamba: Remove ghc-filesystem dependency
------------------------+----------------------
 Reporter:  ryandesign  |      Owner:  l2dy
     Type:  defect      |     Status:  assigned
 Priority:  Normal      |  Milestone:
Component:  ports       |    Version:
 Keywords:              |       Port:  libmamba
------------------------+----------------------
 libmamba uses std::filesystem instead of ghc-filesystem as of version
 0.26.0:

 https://github.com/mamba-org/mamba/releases/tag/2022.09.30

 That means libmamba and everything that depends on it now requires macOS
 10.15 or later unless you want to go down the
 `legacysupport.use_mp_libcxx` road.

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Ticket URL: <https://trac.macports.org/ticket/69741>
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