ci: Fix gitflow workflows (#6995)

Author: mydea

.github/workflows/gitflow-sync-develop.yml

@@ -19,6 +19,7 @@ jobs:
     runs-on: ubuntu-20.04
     permissions:
       pull-requests: write
+      contents: write
     steps:
       - name: git checkout
         uses: actions/checkout@v3

.github/workflows/gitflow-sync-master.yml

@@ -21,6 +21,7 @@ jobs:
     runs-on: ubuntu-20.04
     permissions:
       pull-requests: write
+      contents: write
     steps:
       - name: git checkout
         uses: actions/checkout@v3