Fix Dockerfile: run apt and chmod as root, run container as container user.

Dockerfile

@@ -1,5 +1,6 @@
 FROM ghcr.io/ptero-eggs/steamcmd:debian
 
+USER root
 RUN apt-get update \
  && apt-get install -y --no-install-recommends libnss-wrapper \
  && rm -rf /var/lib/apt/lists/*
@@ -7,5 +8,6 @@ RUN apt-get update \
 COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 
+USER container
 WORKDIR /home/container
 ENTRYPOINT ["/entrypoint.sh"]