patch: Update base image to use latest debian

Dockerfile.template

@@ -1,6 +1,6 @@
 # base-image for python on any machine using a template variable,
 # see more about dockerfile templates here: https://www.balena.io/docs/learn/develop/dockerfile/
-FROM balenalib/%%BALENA_MACHINE_NAME%%-python:3-stretch-run
+FROM balenalib/%%BALENA_ARCH%%-python:3-run
 
 # use `install_packages` if you need to install dependencies,
 # for instance if you need git, just uncomment the line below.
@@ -19,7 +19,7 @@ RUN pip install -r requirements.txt
 COPY . ./
 
 # Enable udevd so that plugged dynamic hardware devices show up in our container.
-ENV UDEV=1
+# ENV UDEV=1
 
 # main.py will run when container starts up on the device
 CMD ["python","-u","src/app.py"]