chore(ci): update workflow for upcoming deprecation (#27366)

Issue number: N/A

---------

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## What is the current behavior?
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`set-output` usage is deprecated in favor of environment files.

## What is the new behavior?
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this PR. -->

- Updates the `test-core-screenshot` workflow to remove `set-output` in
favor of environment files.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

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screenshots of how the component looks before and after the change. -->

.github/workflows/actions/test-core-screenshot/action.yml

@@ -54,7 +54,7 @@ runs:
         mkdir updated-screenshots
         cd ../ && rsync -R --progress $(git diff --name-only --cached) core/updated-screenshots
         if [ -d core/updated-screenshots/core ]; then
-          echo "::set-output name=hasUpdatedScreenshots::$(echo 'true')"
+          echo "hasUpdatedScreenshots=$(echo 'true')" >> $GITHUB_OUTPUT
           cd core/updated-screenshots
           zip -q -r ../../UpdatedScreenshots${{ inputs.commandModifier }}-${{ inputs.shard }}-${{ inputs.totalShards }}.zip core
         fi