Update workflow for this repo

Author: khiga8

.github/workflows/test-accessibility-alt-text-bot.yml

@@ -6,12 +6,14 @@ on:
     types: [opened, edited]
   issue_comment:
     types: [created, edited]
+  discussion:
+    types: [created, edited]
 
 jobs:
   accessibility_alt_text_bot:
     name: Check alt text is set on issue or pull requests
     runs-on: ubuntu-latest
-    if: ${{ github.event.issue || github.event.pull_request && github.event.comment.user.login != 'accessibility-bot' }}
+    if: ${{ github.event.issue || github.event.pull_request || github.event.discussion && github.event.comment.user.login != 'accessibility-bot' }}
     steps:
       - name: Check alt text
         uses: github/accessibility-alt-text-bot@main