v0.31.0

Added

• mind init-source sets [source].min-mind-version to the running version
  in the mind.toml it creates.

Changed

• A source whose min-mind-version is newer than the running mind no longer
  fails every verb. meld warns that it may not work as expected and asks
  whether to continue (--yes continues; with no terminal and no --yes it is
  refused). Other verbs warn and carry on. Both point at mind evolve.
• A mind.toml that fails to parse and declares a newer min-mind-version
  now reports the version gap and mind evolve along with the parse error.
• mind evolve refuses to replace a Homebrew-managed binary (one resolved
  under a Cellar directory) and points at brew upgrade mind. evolve --check still reports, with the same pointer when an update is available.
• Update dirs to 7, cached to 4, self_update to 1.3, and toml to
  1.1.8.

Removed

• The unused sha2 dependency.