Add IPv6 support to unprivileged Docker image

The unprivileged image needs to replace port 80 with port 8080
(since unprivileged users cannot bind to port 80).

This fix modifies the sed commands to replace the port 80 listen
directives (both IPv4 and IPv6) with port 8080 equivalents,
ensuring dual-stack support without privilege issues.

Fixes #339

Signed-off-by: Jesse Awan <jesse.awan@sap.com>

Author: I501307

Dockerfile.unprivileged

@@ -6,7 +6,8 @@
 FROM nginx-s3-gateway
 
 # Implement changes required to run NGINX as an unprivileged user
-RUN sed -i "/^server {/a \    listen       8080;" /etc/nginx/templates/default.conf.template \
+RUN sed -i 's/listen[[:space:]]*80;/listen 8080;/g' /etc/nginx/templates/default.conf.template \
+    && sed -i 's/listen[[:space:]]*\[::\]:80;/listen [::]:8080;/g' /etc/nginx/templates/default.conf.template \
     && sed -i '/user  nginx;/d' /etc/nginx/nginx.conf \
     && sed -i 's#http://127.0.0.1:80#http://127.0.0.1:8080#g' /etc/nginx/include/s3gateway.js \
     && sed -i 's,/var/run/nginx.pid,/tmp/nginx.pid,' /etc/nginx/nginx.conf \