Fixes git stale discord workflow (Again!!) (#95449)

## About The Pull Request
This is suffering. Tries to fix
[This](https://github.com/tgstation/tgstation/actions/runs/23323997716)
which occurs after #95415 was merged.

Apparently the output of the script had some secret information &
invalid variables which it could not store causing the announce workflow
to fail. So i filtered out only the essential components

I wish i had a way to test this workflow locally on my fork repo but i
can't. It's trial and error at this point.

## Changelog
N/A

.github/workflows/stale.yml

@@ -40,7 +40,15 @@ jobs:
         uses: actions/github-script@v8
         with:
           script: |
-            return JSON.parse('${{steps.stale.outputs.staled-issues-prs}}').filter(issue => !!issue.pull_request)
+            const pull_requests = JSON.parse('${{steps.stale.outputs.staled-issues-prs}}')
+                                      .filter(issue => !!issue.pull_request)
+                                      .map(pr => ({
+                                          title: pr.title,
+                                          number: pr.number,
+                                          html_url: pr.pull_request.html_url,
+                                      }));
+
+            return JSON.stringify(pull_requests)
 
   announce:
     runs-on: ubuntu-24.04
@@ -64,7 +72,7 @@ jobs:
           steps.secrets_set.outputs.SECRETS_ENABLED
         with:
           webhook_url: ${{ secrets.DISCORD_WEBHOOK }}
-          title: ${{ matrix.pull_request.user.login }} - ${{ matrix.pull_request.title }}
+          title: ${{ matrix.pull_request.title }}
           message: ${{ format('**Pull Request \#{0} automatically marked as stale.**', matrix.pull_request.number) }}
           include_image: false
           show_author: false