Hydra builders are too old for recent nixpkgs

[michaelpj]

I believe that we're on track to fix this via the new virtualized mac builders, but this is a tracking issue for how things are progressing.

See also:

• Try 19.03 tools#4
• Build on OSX IntersectMBO/plutus#1076

[michaelpj]

Any update on this?

[michaelpj]

Any updates? @cleverca22, perhaps?

[disassembler]

sarov is now mojave. New mac minis arrived today. I'm closing this out.