osx builds no longer working

[Tim Docker]

I've been relying on this github action for my ADL system builds with good results. Unfortunately osx builds have stopped working. An example build is here:

https://github.com/timbod7/adl/runs/911211010?check_suite_focus=true

with the following error:

Run mstksg/setup-stack@v1
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed

  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
curl: (35) Server aborted the SSL handshake
tar: */stack: Not found in archive
tar: Error exit delayed from previous errors.
##[error]Command failed: curl --insecure -L https://get.haskellstack.org/stable/osx-x86_64.tar.gz | tar xz --strip-components=1 --include '*/stack' -C /Users/runner/.local/bin
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed

  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
curl: (35) Server aborted the SSL handshake
tar: */stack: Not found in archive
tar: Error exit delayed from previous errors.

It doesn't appear to be a transient problem. It's been happening consistently for several days, and I'm seeing the same problem also on other projects.