infra: actions: fix docker changes detector so it doesnt always build on force pushes

.gitea/workflows/gentoo-utils.yml

@@ -16,6 +16,8 @@ jobs:
         id: image-changes
         # build image only if 1. changes are detected or 2. an image for the working branch doesnt exist
         run: |
+          git --no-pager log --oneine
+          echo "BEFORE = ${{ gitea.event.before }}"
           branch_name="${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}"
           default_branch_name="${{ gitea.event.repository.default_branch }}"
           image_tag=latest