Response Content-Type check is too strict

[sabadriwan]

Description of the problem:

Currently the library checks the response Content-Type too strictly:

if ($this->getResponseContentType() === 'application/jwt') {
    // ...
}

However, some servers return a Content-Type with additional parameters, for example:

Content-Type: application/jwt; charset=utf-8

Proposed Solution

Relax the check so that it accepts Content-Types starting with application/jwt:

if (strpos($this->getResponseContentType(), 'application/jwt') === 0) {
    // ...
}

This will correctly match both application/jwt and application/jwt; charset=utf-8.

See PR : #493

Technical notes

• We considered using str_contains for readability, but since the library still supports PHP 7, we chose strpos for compatibility.
• If/when PHP 7 support is dropped, the condition could be updated to str_contains for clarity.