PHP 8.5 compatibility: deprecation warnings

## Deprecation notices observed
dependencies shipped inside LoginPress Pro's Social Login add-on. They contain the bulk of the deprecation notices — chiefly implicitly-nullable parameter types (Type $x = null, deprecated since PHP 8.4), plus curl_close(), __wakeup(), $http_response_header, and a (boolean) cast. They still execute on 8.5 but are the main source of noise.

## Steps to reproduce
1. Load the library on PHP 8.5
2. [ Do OAuth and verify ]

## Expected
No PHP 8.5 deprecation notices when using supported library versions.

## Actual
Deprecation noise on PHP 8.5 (still works, but logs are flooded).

## Context
Bundled in WordPress plugin LoginPress Pro for social login .
Happy to test a patch or pre-release.

Start by loading the library on PHP 8.5 and exercising the OAuth flow described in the reproduction steps. Inspect the dependency code responsible for the implicitly nullable parameters, curl_close(), __wakeup(), $http_response_header, and boolean cast notices; done means supported library versions produce no PHP 8.5 deprecation notices while OAuth still works.

Written by the indexing model from the issue text.