Update to sb-chart-block v1.3.1 for support for PHP 8.4 and a minor security fix

Changes
| Change | Reference |
|---|---|
| Changed: Run esc_attr() against the classNames attribute. Props: Peter Thaleikis (Wordfence) | bobbingwide/sb-chart-block#38 |
| Changed: Support PHP 8.4’s str_getcsv() changes | bobbingwide/sb-chart-block#38 |
Tested
- Tested: With WordPress 6.8 and WordPress Multisite
- Tested: With PHP 8.3 and PHP 8.4
- Tested: With PHPUnit 9.6
