admin: Switch to jmertic's slack notifier action (AcademySoftwareFoundation#4079)

The one we were using is broken. John's is surely the GOAT notifier.

---------

Signed-off-by: Larry Gritz <lg@larrygritz.com>
Signed-off-by: John Mertic <jmertic@linuxfoundation.org>
Co-authored-by: John Mertic <jmertic@linuxfoundation.org>
Signed-off-by: Peter Kovář <peter.kovar@reflexion.tv>

Author: 2 people

.github/workflows/release-notice.yml

@@ -19,5 +19,8 @@ jobs:
     - name: Notify Slack
       id: slack
       with:
-        slack_webhook_url: ${{ secrets.SLACK_WEBHOOK_RELEASES_URL }}
-      uses: fedecalendino/slack-release-notifier@8329c1c2d20055ff874ce3eaed7021735d17069d # v2.1.0
+        project_name: "OpenImageIO"
+        slack_bot_token: ${{ secrets.SLACK_BOT_TOKEN }}
+        slack_channel: "#release-announcements"
+        project_logo: "https://artwork.aswf.io/projects/openimageio/icon/color/openimageio-icon-color.png"
+      uses: jmertic/slack-release-notifier@main