Follow-up new member (Qiskit#528)

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### Summary
When project submission is accepted, adding a comment about what the
project maintainer can to follow-up the Ecosystem.


### Details and comments
- [x] Create new job in submission wf
- [x] Tests
[run](#195 (comment))

---
Closes Qiskit#525

---------

Co-authored-by: Frank Harkins <[email protected]>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: frankharkins <[email protected]>
Co-authored-by: github-actions <[email protected]>

.github/workflows/ecosystem-submission.yml

@@ -9,14 +9,14 @@ name: Ecosystem | Submission check
 
 on:
   issues:
-    types: [opened, edited, reopened]
+    types: [opened, edited, reopened, closed]
 
 jobs:
   submission_workflow:
     concurrency:
       group: ci-${{ github.event.issue.title }}
       cancel-in-progress: true
-    if: startsWith(github.event.issue.title, '[Submission]:')
+    if: (startsWith(github.event.issue.title, '[Submission]:') && github.event.action != 'closed')
     runs-on: ubuntu-latest
     env:
       tox_env: "py39"
@@ -233,3 +233,31 @@ jobs:
       with:
         issue-number: ${{ github.event.issue.number }}
         body-path: "summary_output.md"
+
+  followup_workflow:
+    concurrency:
+      group: ci-${{ github.event.issue.title }}
+      cancel-in-progress: true
+    if: |
+      (startsWith(github.event.issue.title, '[Submission]:') && github.event.action == 'closed'
+      && contains(github.event.issue.labels.*.name, 'submission')
+      && contains(github.event.issue.labels.*.name, 'ready'))
+    runs-on: ubuntu-latest
+    steps:
+    - name: Create comment on success
+      uses: peter-evans/create-or-update-comment@v3
+      with:
+        issue-number: ${{ github.event.issue.number }}
+        body: |
+          hello @${{ github.event.issue.user.login }}! You joined the Qiskit Ecosystem a little while ago and I just wanted to check in and let you know of some follow up actions you can take to make the most of joining the program, if you're interested:
+
+          :speech_balloon: Join other Qiskit ecosystem developers in the [Slack channel #qiskit-ecosystem](https://qiskit.slack.com/archives/C04RHE56N93) (if you are not in the Qiskit workspace yet, you can sign up here: https://qisk.it/join-slack)
+
+          :brain: Help us define the future of the Qiskit Ecosystem: we recently started an RFC on how the Ecosystem should be structured. It is very draft-y at the moment, but you can subscribe for notifications here [Qiskit/RFCs#46](https://github.com/Qiskit/RFCs/pull/46) to participate in that discussion.
+
+          :mega: Would you like to showcase your project to the Qiskit community? A couple of things you can do to raise awareness for your project:
+
+          * [write a blog for your project](https://github.com/qiskit-community/ecosystem/wiki/Write-a-Blog-for-your-Project) (reach out to Abby Mitchell via slack or [email](mailto:[email protected]) if you'd like to be featured on the Qiskit Medium)
+          * Participate in [Qiskit Demoday](https://github.com/Qiskit/feedback/wiki/Qiskit-DemoDays). (reach out to Luciano Bello via slack or [email](mailto:[email protected]) to request a slot to demo your project)
+
+          Great having you as a part of the ecosystem!