The Linkedin API now uses versioning and will deprecate the legacy version on Feb, 28.

I have migrated using setApiHeaders, but so not everyone has to read up on this themselves, I am creating this PR.

What I have tested already:

• Create a posts
• Upload assets
• Login with Linkedin
• Read profile / group data

Some more testing for deprecations might be needed.

Sources:
https://www.linkedin.com/developers/news/featured-updates/versioning-content-launch
https://learn.microsoft.com/en-us/linkedin/marketing/versioning

For everyone else reading this:

// Change the API endpoint to the new versioned endpoint
$this->client->setApiRoot("https://api.linkedin.com/rest/");
// Set the API headers to use the new versioning
$this->client->setApiHeaders([
 'Content-Type' => 'application/json',
 'x-li-format' => 'json',
 "LinkedIn-Version" => "202208",
]);```