[CI] use specialized image for ruff, run tests in their own step

.woodpecker/workflow.yaml

@@ -3,16 +3,19 @@ when:
     branch: main
 
 steps:
-  - name: lint-and-test
+  - name: lint
+    image: pipelinecomponents/ruff
+    commands:
+      - ruff check src
+
+  - name: test
     image: python:3.13-slim
     environment:
       PYTHONDEVMODE: 1
       DJANGO_SETTINGS_MODULE: dx.settings
       DJANGO_CONFIGURATION: Dev
     commands:
-      - python -m venv venv
+      - python -m venv --upgrade-deps --without-scm-ignore-files venv
       - /bin/bash -c "source venv/bin/activate"
-      - python -m pip install --upgrade pip
       - python -m pip install -r requirements/test.txt
-      - ruff check src
       - python -m pytest