Pin the OSX version used on the CI

[thufschmitt]

Motivation

Work around cachix/install-nix-action#183

Checklist for maintainers

Maintainers: tick if completed or explain if not relevant

• agreed on idea
• agreed on implementation strategy
• tests, as appropriate
  • functional tests - tests/**.sh
  • unit tests - src/*/tests
  • integration tests - tests/nixos/*
• documentation in the manual
• documentation in the internal API docs
• code and comments are self-explanatory
• commit message explains why the change was made
• new feature or incompatible change: updated release notes

Priorities

Add 👍 to pull requests you find important.

[abathur]

install-nix-action has cut a release that might circumvent the need to pin? See:

• https://github.com/cachix/install-nix-action/releases/tag/v22
• MacOS-12 fix & Nix 2.16.1 cachix/install-nix-action#184

[domenkozar]

Fixed on master.