feat(docker): run docker image as non-root with 'akhq' user (#494)

Dockerfile

@@ -3,6 +3,11 @@ FROM openjdk:11-jre-slim
 WORKDIR /app
 COPY docker /
 ENV MICRONAUT_CONFIG_FILES=/app/application.yml
-USER 10001
+# Create user
+RUN useradd -ms /bin/bash akhq
+# Chown to write configuration
+RUN chown -R akhq /app
+# Use the 'akhq' user
+USER akhq
 ENTRYPOINT ["docker-entrypoint.sh"]
 CMD ["./akhq"]