Replace deprecated gh actions

[pnhatminh]

Pull Request

Related issue

Fixes #678

What does this PR do?

• Replace deprecated github action command with newly defined command.

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• [x] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
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Thank you so much for contributing to Meilisearch!

[pnhatminh]

At the first glance, I thought that I could define the env variable as one desired. So it should be $GITHUB_OUTPUT for every env variables that I would use in the following up command, am I right?

[pnhatminh]

@curquiza I added a sample code here for clarification

[bors[bot]]

Build succeeded:

• Run Clippy
• Run Rustfmt
• Tests on macos-latest
• Tests on ubuntu-20.04
• Tests on windows-latest