drone: simplify lint

.drone.yml

@@ -2,14 +2,10 @@ kind: pipeline
 name: default
 
 steps:
-- name: isort
-  image: python:alpine
-  commands:
-  - pip install isort
-  - isort --check-only --diff .
-- name: pylint
+- name: lint
   image: alpine
   commands:
   - apk add --no-cache python3 py3-lxml py3-pip py3-wheel py3-enchant hunspell-en
+  - isort --check-only --diff .
   - pip3 install --no-cache-dir .[full] .[dev]
   - pylint morss --rcfile=.pylintrc --disable=C,R,W --fail-under=8