ci: Use GITHUB_OUTPUT envvar instead of set-output command (#100)

PR-URL: #100

`save-state` and `set-output` commands used in GitHub Actions are deprecated and [GitHub recommends using environment files](https://github.blog/changelog/2023-07-24-github-actions-update-on-save-state-and-set-output-commands/).

This PR updates the usage of `::set-output` to `"$GITHUB_OUTPUT"`

Instructions for envvar usage from GitHub docs:

https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-output-parameter

.github/workflows/ci.yml

@@ -180,7 +180,7 @@ jobs:
         echo "node@$(node -v)"
         echo "npm@$(npm -v)"
         npm -s ls ||:
-        (npm -s ls --depth=0 ||:) | awk -F'[ @]' 'NR>1 && $2 { print "::set-output name=" $2 "::" $3 }'
+        (npm -s ls --depth=0 ||:) | awk -F'[ @]' 'NR>1 && $2 { print "" $2 "=" $3 }' >> "$GITHUB_OUTPUT"
 
     - name: Run tests
       shell: bash