chore(deps): add dedicated lock files for older Elixir versions

[solnic]

This is needed after all so that we'll be able to bump various deps with no version conflicts.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Unsupported flag on Elixir 1.13

High Severity

The CI download step always runs mix deps.get --check-locked, including on the Elixir 1.13 matrix job. That flag was added in Elixir 1.14, while this project still tests 1.13 and already skips --check-locked for older versions elsewhere in mix.exs.

 

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