ci: fix release pipeline, add permissions to GH token

Author: dgniewek

.github/workflows/prepare-release.yml

@@ -13,6 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write # to create branch, tag and push the changes
+      pull-requests: write # to create pull request
     strategy:
       matrix:
         python-version: [3.9]

.github/workflows/publish.yml

@@ -8,6 +8,8 @@ on:
 jobs:
   deploy:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write # to push to develop, create releases and tags
     strategy:
       matrix:
         python-version: ["3.9"]