Fix PHP deprecation notice about passing null to parameter of type st…

[donnapep]

Proposed Changes

Fixes a deprecation notice:

PHP Deprecated:  parse_str(): Passing null to parameter #1 ($string) of type string is deprecated in /Users/donnapep/Local Sites/senseitheme/app/public/wp-content/plugins/sensei/includes/class-sensei-utils.php on line 2921

Testing Instructions

1. Ensure you're using PHP 8.1+.
2. Go to Appearance > Editor.
3. Ensure the above deprecation notice is not logged.

Note that the following PHP warnings are still logged, but this PR does not attempt to fix those:

PHP Warning:  Undefined property: stdClass::$modified in /Users/donnapep/Local Sites/senseitheme/app/public/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 766
PHP Warning:  DOMDocument::loadHTML(): Unexpected end tag : p in Entity, line: 1 in /Users/donnapep/Local Sites/senseitheme/app/public/wp-content/plugins/sensei/includes/blocks/class-sensei-blocks.php on line 225

Pre-Merge Checklist

• PR title and description contain sufficient detail and accurately describe the changes
• Acceptance criteria is met
• Decisions are publicly documented
• Adheres to coding standards (PHP, JavaScript, CSS, HTML)
• All strings are translatable (without concatenation, handles plurals)
• Follows our naming conventions (P6rkRX-4oA-p2)
• Hooks (p6rkRX-1uS-p2) and functions are documented
• New UIs are responsive and use a mobile-first approach
• New UIs match the designs
• Different user privileges (admin, teacher, subscriber) are tested as appropriate
• Legacy courses (course without blocks) are tested
• Code is tested on the minimum supported PHP and WordPress versions
• User interface changes have been tested on the latest versions of Chrome, Firefox and Safari
• "Needs Documentation" label is added if this change requires updates to documentation
• Known issues are created as new GitHub issues

[github-actions]

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[github-actions]

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[github-actions]

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