Automate retrospective issue creation

Signed-off-by: Sayali Gaikawad <gaiksaya@amazon.com>

.github/ISSUE_TEMPLATE/release_retrospective_template.md

@@ -0,0 +1,14 @@
+---
+name: Release retrospective
+title: "[Retrospective] Release Version {{ env.VERSION }}"
+labels: untriaged, release, v{{ env.VERSION }}
+---
+
+### **Related release issue?**
+{{ env.RELEASE_ISSUE_URL }}
+
+### **How to use this issue?**
+Please add comments to this [Retro Board](https://github.com/orgs/opensearch-project/projects/205/views/4), they can be small or large in scope. Honest feedback is important to improve our processes, suggestions are also welcomed but not required.
+
+### **What will happen to this issue post release?**
+There will be a discussion(s) about how the release went and how the next release can be improved. Then this issue will be updated with the notes of that discussion along side action items.

.github/workflows/releases.yml

@@ -26,10 +26,21 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: dblock/create-a-github-issue@v3.0.0
+        id: release-issue
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           VERSION: ${{ matrix.release_version }}
         with:
           search_existing: all
           update_existing: false
           filename: .github/ISSUE_TEMPLATE/release_template.md
+      - uses: dblock/create-a-github-issue@v3.0.0
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          VERSION: ${{ matrix.release_version }}
+          RELEASE_ISSUE_URL: ${{ steps.release-issue.outputs.url }}
+        with:
+          search_existing: all
+          update_existing: false
+          filename: .github/ISSUE_TEMPLATE/release_retrospective_template.md
+