🐛 Image shall be set for each CI step

backend/.woodpecker/.lint.yaml

@@ -3,10 +3,9 @@ when:
     branch:
       exclude: [master, release/*]
 
-image: python:3.12-alpine
-
 steps:
   - name: prepare
+    image: python:3.12-alpine
     command: |
       wget -O - -q https://raw.githubusercontent.com/reviewdog/reviewdog/master/install.sh | sh -s latest
       pip install poetry
@@ -14,12 +13,14 @@ steps:
       poetry install --only=linters --no-root
 
   - name: ruff
+    image: python:3.12-alpine
     failure: ignore
     secrets: ["reviewdog_gitea_api_token", "gitea_address"]
     commands: |
       poetry run ruff --output-format sarif . | ./bin/reviewdog -f sarif -reporter gitea-pr-review -filter-mode nofilter
 
   - name: mypy
+    image: python:3.12-alpine
     failure: ignore
     secrets: ["reviewdog_gitea_api_token", "gitea_address"]
     commands: |