[WIP] Fix syntax errors in run_test_case.yaml

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

There seem to be syntax errors in the GitHub Actions workflow run_test_case.yaml file based on the provided diff. Specifically:

1. The introduction of a strategy matrix combination (os, arch, otp, builder, elixir) in the jobs block needs to be validated.
2. The container field dynamically references matrix variables, which should follow the correct syntax for interpolating variables.
3. The uses actions have been updated to newer versions. Ensure these updates still follow correct syntax.
4. Review the entire YAML structure to ensure alignment and sequence consistency.

This pull request was created from Copilot chat.

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