Add PHP 8.4 support, fix deprecations

[jameswilson]

There are several deprecation warnings when using PHP 8.4 and the latest php-jira-rest-client version 5.9:

Deprecated: JiraRestApi\JiraClient::__construct(): Implicitly marking parameter
$configuration as nullable is deprecated, the explicit nullable type must be used instead
in /var/www/html/vendor/lesstif/php-jira-rest-client/src/JiraClient.php on line 62

Deprecated: JiraRestApi\JiraClient::__construct(): Implicitly marking parameter
$logger as nullable is deprecated, the explicit nullable type must be used instead
in /var/www/html/vendor/lesstif/php-jira-rest-client/src/JiraClient.php on line 62

Deprecated: JiraRestApi\JiraClient::exec(): Implicitly marking parameter
$post_data as nullable is deprecated, the explicit nullable type must be used instead
in /var/www/html/vendor/lesstif/php-jira-rest-client/src/JiraClient.php on line 188

Deprecated: JiraRestApi\JiraClient::exec(): Implicitly marking parameter
$custom_request as nullable is deprecated, the explicit nullable type must be used instead
 in /var/www/html/vendor/lesstif/php-jira-rest-client/src/JiraClient.php on line 188

Deprecated: JiraRestApi\JiraClient::exec(): Implicitly marking parameter
$cookieFile as nullable is deprecated, the explicit nullable type must be used instead
in /var/www/html/vendor/lesstif/php-jira-rest-client/src/JiraClient.php on line 188

Deprecated: JiraRestApi\JiraClient::authorization(): Implicitly marking parameter
$cookieFile as nullable is deprecated, the explicit nullable type must be used instead
in /var/www/html/vendor/lesstif/php-jira-rest-client/src/JiraClient.php on line 441

Deprecated: JiraRestApi\JiraClient::download(): Implicitly marking parameter
$cookieFile as nullable is deprecated, the explicit nullable type must be used instead
in /var/www/html/vendor/lesstif/php-jira-rest-client/src/JiraClient.php on line 516