mtest 1.2.0

What's Changed

• build(pixi): move to Mojo 1.1.0 by @mikeleppane in #53
• chore(checks): add toolchain guardrails and split the README by @mikeleppane in #54
• docs(agents): retro follow-ups for the review gate and stale copies by @mikeleppane in #55
• ci(ci): bump the reviewed action pins Dependabot proposed by @mikeleppane in #56
• fix(release): make public verification and the timeout scenario pass honestly by @mikeleppane in #57
• build(release): cut 1.2.0 by @mikeleppane in #58
• fix(exec): tolerate XNU's EPERM from the parent's setpgid race by @mikeleppane in #60
• ci(ci): install the pixi upstream's requires-pixi names by @mikeleppane in #59

Full Changelog: v1.1.0...v1.2.0