Fix workflow to fetch all repo

Author: therve

.github/workflows/prepare_release.yml

@@ -22,6 +22,8 @@ jobs:
           app_id: ${{ secrets.PIPELINE_GITHUB_APP_ID }}
           private_key: ${{ secrets.PIPELINE_GITHUB_APP_PRIVATE_KEY }}
       - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
 
       - name: Setup Git
         run: |