fix Dockerfile

Dockerfile

@@ -24,14 +24,15 @@ RUN \
   useradd -m -r -u $ArduinoUID -g $USER -G dialout $USER
 
 USER $USER
-WORKDIR ~
+WORKDIR /home/${USER}
 
 RUN \
   arduino-cli config init 
 
-COPY arduino-cli.yaml ~/.arduino15/
+COPY arduino-cli.yaml /home/${USER}/.arduino15/
 
 RUN \
+  pwd && \
   ls -l ~/.arduino15 && \
   arduino-cli core update-index && \
   arduino-cli core install arduino:avr && \