made use of ARG gid_input

rfidac/Dockerfile

@@ -1,8 +1,8 @@
 FROM arm32v6/alpine
 
-ARG gid_input=${gid_input}
+ARG gid_input=105
 
-RUN echo "rfidac:x:100:105:RFIC AC,,,:/opt:/sbin/nologin" >> /etc/passwd \
+RUN echo "rfidac:x:100:$gid_input:RFIC AC,,,:/opt:/sbin/nologin" >> /etc/passwd \
  && apk add --no-cache --update bash python3 \
  && pip3 install --upgrade pip setuptools \
  && apk add --no-cache linux-headers gcc musl-dev python3-dev \