ci: fix issue response (#956)

Fix gh command failure when no github repository can be found.

.github/workflows/issue-comment.yml

@@ -25,4 +25,4 @@ jobs:
     steps:
       - name: respond to issue
         run: |
-          gh issue comment ${{ inputs.issue-number }} --body "${{ inputs.message }}"
+          gh issue -R ${{ github.repository }} comment ${{ inputs.issue-number }} --body "${{ inputs.message }}"