projects: serve badge with same protocol as resolver

Instead of request.is_secure use settings.PUBLIC_DOMAIN_USES_HTTPS
to find out if we should serve the badge under https or not.
That matches what the resolver is doing and works here.

Author: xrmx

readthedocs/projects/views/public.py

@@ -90,7 +90,8 @@ def get_context_data(self, **kwargs):
             user=self.request.user, project=project)
 
         protocol = 'http'
-        if self.request.is_secure():
+        use_https = getattr(settings, 'PUBLIC_DOMAIN_USES_HTTPS', False)
+        if use_https:
             protocol = 'https'
 
         version_slug = project.get_default_version()