Replace deprecated ::set-output with $GITHUB_OUTPUT (#1361)

## Summary

- Replace deprecated `::set-output` workflow command with the
recommended `>> $GITHUB_OUTPUT` syntax in
`.github/workflows/integration-tests.yml`
- The `::set-output` command was [deprecated by
GitHub](https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/)
due to a log injection vulnerability (untrusted data could be injected
into the output)
- The new `$GITHUB_OUTPUT` environment file approach is the recommended
replacement

## Test plan

- [ ] Verify the `check_secrets` job still correctly sets the
`has_token` output
- [ ] Verify downstream jobs that depend on `has_token` output continue
to work

NO_CHANGELOG=true

This pull request was AI-assisted by Isaac.

Signed-off-by: Hector Castejon Diaz <hector.castejon@databricks.com>

Author: hectorcast-db

.github/workflows/integration-tests.yml

@@ -25,10 +25,10 @@ jobs:
         run: |
             if [ -z "${{ secrets.DECO_WORKFLOW_TRIGGER_APP_ID }}" ] || [ -z "${{ secrets.DECO_TEST_APPROVAL_APP_ID }}" ]; then
               echo "Required secrets are missing. User has no access to secrets."
-              echo "::set-output name=has_token::false"
+              echo "has_token=false" >> $GITHUB_OUTPUT
             else
               echo "All required secrets are set. User has access to secrets."
-              echo "::set-output name=has_token::true"
+              echo "has_token=true" >> $GITHUB_OUTPUT
             fi
 
   trigger-tests: