Ignore phpcs file system errors

[m1r0]

Resolves https://github.com/Automattic/sensei-security/issues/23

Plugin Check is suggesting to use WP_Filesystem instead of the system calls. I'm ignoring it because the class doesn't provide the needed functionality.

Proposed Changes

• Ignore the phpcs system calls errors.

Testing Instructions

1. Install the Plugin Check plugin.
2. Go to Tools > Plugin Check.
3. Select Sensei LMS from the dropdown and ensure Plugin Repo is selected.
4. Click Check it! button.
5. Make sure there are no WP_Filesystem errors.

Pre-Merge Checklist

• PR title and description contain sufficient detail and accurately describe the changes
• 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
• Code is tested on the minimum supported PHP and WordPress versions

[github-actions]

Test the previous changes of this PR with WordPress Playground.

[donnapep]

Easy peasy!