Update DeterminateSystems/magic-nix-cache-action action to v12

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
DeterminateSystems/magic-nix-cache-action	action	major	v11 -> v12

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Release Notes

DeterminateSystems/magic-nix-cache-action (DeterminateSystems/magic-nix-cache-action)

v12

Compare Source

What's Changed

• update readme to use magic-nix-cache action by @​phanirithvij in https://github.com/DeterminateSystems/magic-nix-cache-action/pull/136
• Fix broken link in README by @​lucperkins in https://github.com/DeterminateSystems/magic-nix-cache-action/pull/141

Plus assorted dependency updates.

New Contributors

• @​phanirithvij made their first contribution in https://github.com/DeterminateSystems/magic-nix-cache-action/pull/136

Full Changelog: DeterminateSystems/magic-nix-cache-action@v11...v12

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