Fix Dockerfile

test/lint/pylint/Dockerfile

@@ -5,5 +5,6 @@ COPY requirements.txt /
 RUN apk add --no-cache \
       build-base=0.5-r2 \
       git=2.34.1-r0 \
+      libffi-dev \
       bc=1.07.1-r1 && \
     pip3 install --no-cache-dir -r requirements.txt