Greet new contributors (#58)

* Greet new contributors

Added a workflow to greet new contributors and first time issuers.

* add Token + msg change

* Change welcome action

* Use official GH action

.github/workflows/welcome.yml

+name: Welcome
+on:
+  pull_request:
+    types: [opened]
+  issues:
+    types: [opened]
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/first-interaction@v1.2.0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          issue-message: |
+            👋 @{{ author }}
+             Thanks for opening your first issue here! If you are reporting a bug, please make sure to include steps on how to reproduce it! :D
+
+          pr-message: |
+            👋 @{{ author }}
+            Thanks for opening this pull request! We will review it as soon as we can :3
+            Please check out our contributing guidelines in the meantime.
+
+         # FIRST_PR_MERGED: |
+         #   🎉 @{{ author }}
+         #   Congrats on getting your first pull request merged! We are proud of you :3 ❤️