Run lint target independently using an upstream alpine image.

Earthfile

@@ -21,7 +21,9 @@ INSTALL:
 	RUN dpkg -i deb_dist/*.deb
 
 lint:
-	FROM +build
+	FROM docker.io/library/python:3.10-alpine
+	COPY . /src/stdeb
+	WORKDIR /src/stdeb
 	RUN python3 -m pip install -r requirements.txt
 	RUN ruff format --check || true
 	RUN ruff check || true