Fix GitHub Discussions category for CI-CD notifications

Update release-post-comment.yml to post to the CI-CD category instead
of Announcements category.

Changes:
- Line 21: Update default discussion_category_id to CI-CD category
- Line 538: Update fallback DISCUSSION_CATEGORY_ID to CI-CD category
- Update description: "announcements" → "CI-CD notifications"

Category ID changed:
- Old (Announcements): DIC_kwDOACA_5s4CXquL
- New (CI-CD): DIC_kwDOACA_5s4Cxk-W

This ensures future release posts appear in:
https://github.com/crossbario/autobahn-python/discussions/categories/ci-cd

Fixes posting to wrong category as seen in:
#1759

Author: oberstet

.github/workflows/release-post-comment.yml

@@ -15,10 +15,10 @@ on:
         required: false
         type: string
       discussion_category_id:
-        description: "GitHub Discussions category ID for announcements"
+        description: "GitHub Discussions category ID for CI-CD notifications"
         required: false
         type: string
-        default: "DIC_kwDOACA_5s4CXquL"  # Announcements category in autobahn-python repo
+        default: "DIC_kwDOACA_5s4Cxk-W"  # CI-CD category in autobahn-python repo
 
 permissions:
   pull-requests: write  # Required for posting PR comments
@@ -535,7 +535,7 @@ jobs:
       - name: Post to GitHub Discussions
         uses: actions/github-script@v7
         env:
-          DISCUSSION_CATEGORY_ID: ${{ github.event.inputs.discussion_category_id || 'DIC_kwDOACA_5s4CXquL' }}
+          DISCUSSION_CATEGORY_ID: ${{ github.event.inputs.discussion_category_id || 'DIC_kwDOACA_5s4Cxk-W' }}
         with:
           script: |
             const fs = require('fs');