ci: welcome new contributors

.github/workflows/welcome.yaml

@@ -0,0 +1,17 @@
+name: Welcome
+on:
+  pull_request_target:
+    types: [opened]
+jobs:
+  welcome:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: wow-actions/welcome@v1.3.0
+      with:
+        FIRST_PR_COMMENT: |
+          Hello @{{ author }}. Thank you for contributing to this project! 💛 I'll review your changes when time permits.
+
+          By contributing, you agree to the [Developer Certificate of Origin](https://developercertificate.org)
+          and your code being licensed under the [MIT license](https://raw.githubusercontent.com/Realiserad/fish-ai/main/LICENSE).
+
+          If this sounds like greek, please spend a minute or two to read through these documents.