Use favicon as avatar for Discord webhooks

.github/workflows/main.yml

@@ -151,5 +151,6 @@ jobs:
             Content-Type: application/json; charset=UTF-8
           body: |
             {
+              "avatar_url": "https://raw.githubusercontent.com/${{ github.event.repository.full_name }}/${{ github.ref_name }}/favicon.png",
               "content": "**${{ github.event.repository.name }}** new version released!\nVersion: `${{ github.ref_name }}`\nChangelog: <${{ github.event.repository.html_url }}/blob/${{ github.ref_name }}/Changelog.md>"
             }