fix(workflow): replace deprecated set-output command

[codewithbear]

Fixes for the issues
openfoodfacts/smooth-app#5211
openfoodfacts/openfoodfacts-infrastructure#484

Created by AI Prompt

set-output workflow action is deprecated and should not be used. Instead environment variables should be used. Do not introduce any new files!

Examples: 
<example_before> run: echo "::set-output name=VERSION_NAME::${{ env.VERSION_NAME }}" && echo "::set-output name=VERSION_CODE::${{ env.VERSION_CODE }}" </example_before> 
<example_fixed> run: echo "VERSION_CODE=${{ env.VERSION_CODE }}" >> $GITHUB_ENV && echo "VERSION_NAME=${{ env.VERSION_NAME }}" >> $GITHUB_ENV </example_fixed>

This is an automated PR created by Morph (codemorph.dev)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Copilot]

Pull Request Overview

This PR updates the CI workflow to replace the deprecated ::set-output command with the new $GITHUB_OUTPUT mechanism.

• Switches the composer-cache step to write outputs using $GITHUB_OUTPUT
• Removes the old ::set-output usage