v4.2.2: Zstd tar fallback for older runners

A small patch release that fixes archive selection on runners with an older tar and corrects a stale default in the README.

Fixed

Verify tar supports Zstd before picking .tar.zst (#569 by @JackMyers001

The action previously chose the .tar.zst mise archive whenever zstd --version succeeded, then extracted it with tar --zstd. On RHEL 8-compatible runners that ship zstd 1.4.4 alongside GNU tar 1.30, the --zstd option isn't recognized and installation failed.

Detection now runs both checks:

zstd --version
tar --zstd --version

If either fails, the action falls back to the .tar.gz archive. No configuration change is required — existing workflows on affected runners just start working again. Fixes #568.

Documentation

• Update the cache_key_prefix example in the README to reflect the current default of mise-v1 (previously documented as mise-v0) (#570 by @muzimuzhi).

New Contributors

• @JackMyers001 made their first contribution in #569
• @muzimuzhi made their first contribution in #570

Full Changelog: v4.2.1...v4.2.2