try to run without root user

Dockerfile

@@ -51,7 +51,7 @@ RUN echo "deb-src http://deb.debian.org/debian bullseye main contrib" >> /etc/ap
 		--with-filedescriptors=48000 \
 		--enable-delay-pools \
 		--with-large-files \
-                --with-pidfile=/tmp \
+                --with-pidfile=/tmp/squid.pid \
                 --with-default-user=squid \
 		--enable-removal-policies="lru,heap" \
     && make \