[ticket/13231] Update the dependencies of the migration contact_admin_form

PHPBB3-13231
[ticket/13227] Properly handle curlwrapper headers in remote avatars

Read a bit of the file to ensure header values are populated and then
handle headers in the nested array structure too.

PHPBB3-13227
Merge pull request #3083 from Nicofuma/ticket/13231

[ticket/13231] Update the dependencies of the migration contact_admin_form
Merge pull request #3085 from naderman/ticket/13227

[ticket/13227] Properly handle curlwrapper headers in remote avatars
Merge branch 'prep-release-3.1.0' into develop-ascraeus

* prep-release-3.1.0:
  [ticket/13227] Properly handle curlwrapper headers in remote avatars
  [ticket/13231] Update the dependencies of the migration contact_admin_form