make running tests optional in docker build

Dockerfile

@@ -4,9 +4,11 @@ WORKDIR /extract
 
 COPY . .
 
+ARG run_tests=true
+
 RUN apt-get update && apt-get install -y libzbar0 python3-opencv nano \
     && pip install -r requirements.txt \
-    && /extract/run_pytest.sh
+    && if [[ "$run_tests" == "true" ]] ; then /extract/run_pytest.sh ; else echo "Not running tests..." ; fi
 
 WORKDIR /files