Update Dockerfile

Dockerfile

@@ -5,14 +5,15 @@ ENV NAPALM_USERNAME netbox-napalm
 RUN apk add --no-cache \
         libressl-dev \
         musl-dev \
-        libffi-dev && \
+        libffi-dev \
+        alpine-sdk && \
     pip install --no-cache-dir cryptography==2.1.4 && \
     apk del \
         libressl-dev \
         musl-dev \
         libffi-dev
 
-RUN apk add git zlib alpine-sdk python3-dev libxml2-dev libxslt-dev && pip3 install --upgrade napalm cffi napalm-dellos10
+RUN apk add git zlib python3-dev libxml2-dev libxslt-dev && pip3 install --upgrade napalm cffi napalm-dellos10
 RUN pip3 install nextbox-ui-plugin
 RUN apk add py3-pillow
 WORKDIR /tmp