Fix actions/first-interaction input

Author: swissspidy

.github/workflows/reusable-welcome-new-contributors.yml

@@ -13,7 +13,7 @@ jobs:
         uses: actions/first-interaction@v3
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}
-          pr_message: |
+          issue_message: |
             Hello! 👋
 
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