Greet new reporters and contributors using actions

Replaces the welcome bot

.github/workflows/greetings.yml

@@ -0,0 +1,25 @@
+name: Greetings
+
+on: [pull_request, issues]
+
+jobs:
+  greeting:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/first-interaction@v1
+      with:
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        issue-message: >
+          Hi there! 👋🏼
+          As you're new to this repo, we'd like to suggest that you read our [code of conduct](https://github.com/containrrr/watchtower/blob/master/CODE_OF_CONDUCT.md)
+          as well as our [contribution guidelines](https://github.com/containrrr/watchtower/blob/master/CONTRIBUTING.md).
+          \n
+          Thanks a bunch for opening your first issue! 🙏
+        pr-message: >
+          Congratulations on opening your first pull request! 🥳\n\n
+          To make sure that your pull request is handled as fast as possible, we recommend that you make sure that you make sure that you've done the following\:\n
+          [ ] Documentation has been updated
+          [ ] Tests have been added to all appropriate places
+          [ ] Changes adhere to our [contribution guidelines](https://github.com/containrrr/watchtower/blob/master/CONTRIBUTING.md)
+
+          Thanks! 🙏🏼