X-Forwarded-Proto is returning `http,https` instead of `https` since nginx version >= `1.23`

[elaman]

Motivation

We recently updated our Drupal website to use wodby/nginx:1.25-5.33.0 instead of wodby/nginx:1.19-5.25.6. Immediately we noticed that sitemap.xml was generated with links using http instead of https.

Investigation

The Simple Sitemap module is using $GLOBALS['base_url'] to generate links, which in turn relies on symfony/http-foundation method Request::isSecure. This method checks X-Forwarded-Proto header for http or https.

Proposed solution

Provide environmental variable to set the value for this header and override the default.

[csandanov]

Sure, let's add it