[MacPorts] #54376: math/gsl documentation variant now depends on Sphinx

[MacPorts]

#54376: math/gsl documentation variant now depends on Sphinx
----------------------+------------------------
  Reporter:  slewsys  |      Owner:  dtakahashi
      Type:  defect   |     Status:  assigned
  Priority:  Normal   |  Milestone:
 Component:  ports    |    Version:
Resolution:           |   Keywords:
      Port:  gsl      |
----------------------+------------------------

Comment (by Schamschula):

 This version gets rid of the +doc variant that cannot be called w/o
 calling a +doc_pythonXX variant.

--
Ticket URL: <https://trac.macports.org/ticket/54376#comment:8>
MacPorts <https://www.macports.org/>
Ports system for macOS