[MacPorts] #57698: Travis: Use the normal MacPorts installer

[MacPorts]

#57698: Travis: Use the normal MacPorts installer
-----------------------------+---------------------
  Reporter:  ryandesign      |      Owner:  admin@…
      Type:  defect          |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  server/hosting  |    Version:
Resolution:                  |   Keywords:
      Port:                  |
-----------------------------+---------------------

Comment (by neverpanic):

 I've kept the tarball that gets extracted and haven't used to official
 installer, but at least those tarballs are now on a more official account,
 plus their generation is automated by a CI in macports-base.

-- 
Ticket URL: <https://trac.macports.org/ticket/57698#comment:12>
MacPorts <https://www.macports.org/>
Ports system for macOS