Update dependency fmt to v12

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
fmt	requires	major	11.2.0 -> 12.0.0

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Configuration

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🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: solvers/cpp/conan.lock

Command failed: conan lock create solvers/cpp/conanfile.txt
/bin/sh: 1: conan: not found