HCE-721 Enable Auto Dependabot Changelogs (#150)

* enable dependabot changelogs

* changelog

* newline

.changelog/150.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+Enable automatic changelog creation for dependabot PRs.
+```

.github/dependabot.yml

@@ -11,8 +11,12 @@ updates:
     schedule:
       # Check for updates to GitHub Actions every weekday
       interval: "daily"
+    labels:
+      - "pr/no-changelog"
 
   - package-ecosystem: "gomod" # See documentation for possible values
     directory: "/" # Location of package manifests
     schedule:
       interval: "daily"
+    labels:
+      - "pr/no-changelog"

.github/workflows/create-dependabot-changelog.yml

@@ -0,0 +1,37 @@
+# Auto generate a changelog entry if the PR was opened by dependabot.
+---
+name: Create Changelog for Dependabot
+
+on:
+  pull_request:
+    types: 
+      - opened
+
+jobs:
+  create_changelog:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.pull_request.user.login == 'dependabot'}}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+          token: ${{ secrets.HCP_SDK_PIPELINE_TOKEN }}
+
+      - name: Configure git
+        env:
+          TOKEN: ${{ secrets.HCP_SDK_PIPELINE_TOKEN }}
+        run: |
+            git config --global advice.detachedHead false
+            git config --global url."https://${TOKEN}:[email protected]/".insteadOf "https://github.com/"
+            git config user.name "github-actions"
+            git config user.email "[email protected]"
+      - name: Create Changelog
+        run: |
+          echo "This is a Dependabot PR. Creating changelog entry on its behalf."
+          touch .changelog/${{ github.event.pull_request.number }}.txt
+          printf '```release-note:improvement%s\n' >> .changelog/${{ github.event.pull_request.number }}.txt
+          printf '${{ github.event.pull_request.title }}%s\n' >> .changelog/${{ github.event.pull_request.number }}.txt
+          printf '```%s\n' >> .changelog/${{ github.event.pull_request.number }}.txt
+          git add .
+          git commit -m "Added changelog entry"
+          git push