test: Improvements to CI Workflow (#2437)

### Changes

This pull request updates the continuous integration workflow
`test.yml`:

- Refine concurrency group specificity to improve efficiency. This
cancels in-progress test runs when changes are committed to a pull
request.
- Rename the test's `Run` step to `Build Package` for clarity to aid in
filtering branch protection rules.
- Update checkout step to use `github.event.pull_request.head.sha` for
`pull_request_target` (and `github.ref` for non-PR triggering events).
- Hardcode `node-version` to 18 rather than use an environment variable.

### References

Updates based on internal feedback and conversations.

### Testing

This pull request applies improvements to the continuous integration
testing for the repository but does not add any additional tests.

### Checklist

* [x] I have read the [Auth0 general contribution
guidelines](https://github.com/auth0/open-source-template/blob/master/GENERAL-CONTRIBUTING.md)
* [x] I have read the [Auth0 Code of
Conduct](https://github.com/auth0/open-source-template/blob/master/CODE-OF-CONDUCT.md)
* [x] All code quality tools/guidelines have been run/followed
* [x] All relevant assets have been compiled

.github/workflows/test.yml

@@ -15,7 +15,7 @@ permissions:
   contents: read
 
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}
 
 jobs:
@@ -29,17 +29,19 @@ jobs:
   run:
     needs: authorize # Require approval before running on forked pull requests
 
-    name: Run
+    name: Build Package
     runs-on: ubuntu-latest
 
     steps:
       - name: Checkout code
         uses: actions/checkout@v3
+        with:
+          ref: ${{ github.event.pull_request.head.sha || github.ref }}
 
       - name: Setup Node
         uses: actions/setup-node@v3
         with:
-          node-version: ${{ env.NODE_VERSION }}
+          node-version: 18
           cache: 'npm'
 
       - name: Install dependencies