Remove sync branches script

With serving UI assets from containers, there is no need to sync branches anymore.

.github/workflows/sync-branches.yml

@@ -1,79 +0,0 @@
-name: Sync branches
-
-on:
-  push:
-    branches:
-      - main
-  workflow_dispatch:
-    inputs:
-      source:
-        description: Source ref (branch or sha)
-        required: true
-        type: string
-      target:
-        description: Target branch
-        required: true
-        type: choice
-        options:
-          - production
-          - stage-stable
-
-
-jobs:
-  check:
-    name: Validate source and target refs
-    timeout-minutes: 1
-    runs-on: ubuntu-latest
-    if: ${{ github.event_name == 'workflow_dispatch' }}
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v3
-        with:
-          ref: ${{ github.event.inputs.source }}
-          fetch-depth: 0
-
-      - name: Check ancestry
-        if: ${{ github.event.inputs.target == 'production' }}
-        run: |
-          if ! git merge-base --is-ancestor ${{ github.event.inputs.source }} origin/main; then
-            echo "Target is production and source ref isn't an ancestor of main"
-            exit 1
-          fi
-          if ! git merge-base --is-ancestor ${{ github.event.inputs.source }} origin/stage-stable; then
-            echo "Target is production and source ref isn't deployed in stage-stable"
-            echo "The main and stage-stable branches should be in sync, please fix"
-            exit 1
-          fi
-
-      - name: Check stage-stable manual sync
-        if: ${{ github.event.inputs.target == 'stage-stable' }}
-        run: |
-          if [ $(git rev-parse ${{ github.event.inputs.source }}) != $(git rev-parse origin/main) ]; then
-            echo "Target is stage-stable and source ref isn't main"
-            exit 1
-          fi
-
-
-  sync:
-    name: Sync source and target refs
-    needs: check
-    if: ${{ github.event_name == 'push' || success() }}
-    timeout-minutes: 5
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v3
-        with:
-          ref: ${{ github.event.inputs.source }}
-          fetch-depth: 0
-
-      - name: Release to production
-        if: ${{ github.event_name == 'workflow_dispatch' && github.event.inputs.target == 'production' }}
-        run: |
-          git push https://${{ secrets.SCHUTZBOT_GH_TOKEN }}@github.com/${{ github.repository }}.git ${{ github.event.inputs.source }}:refs/heads/prod-beta
-          git push https://${{ secrets.SCHUTZBOT_GH_TOKEN }}@github.com/${{ github.repository }}.git ${{ github.event.inputs.source }}:refs/heads/prod-stable
-
-      - name: Sync main to stage-stable
-        if: ${{ github.event_name == 'push' || github.event.inputs.target == 'stage-stable' }}
-        run: |
-          git push https://${{ secrets.SCHUTZBOT_GH_TOKEN }}@github.com/${{ github.repository }}.git origin/main:refs/heads/stage-stable