[Snek] [keith-packard/snek] 52e408: .github: Cache dockerfile

[Keith Packard]

  Branch: refs/heads/debian-qemu
  Home:   https://github.com/keith-packard/snek
  Commit: 52e408ee27728b07c2eab41e1ce8db7665994fcd
      https://github.com/keith-packard/snek/commit/52e408ee27728b07c2eab41e1ce8db7665994fcd
  Author: Keith Packard <keithp at keithp.com>
  Date:   2022-02-12 (Sat, 12 Feb 2022)

  Changed paths:
    M .github/workflows/snek.yml

  Log Message:
  -----------
  .github: Cache dockerfile

Signed-off-by: Keith Packard <keithp at keithp.com>