Fix CI compatibility for Excel 4 and Laravel CSRF middleware

[swilla]

What changed

• Bumped maatwebsite/excel in composer.json from ^3.1 to ^4.0 to align with tapp/filament-form-builder v4.3.3.
• Updated panel middleware from VerifyCsrfToken to PreventRequestForgery in LmsPanelProvider for current Laravel compatibility.

Why

This branch addresses CI and dependency compatibility issues after the Form Builder Excel 4.x support release. These updates ensure dependency resolution succeeds and the panel middleware uses the supported framework class.

Made with Cursor

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Note

Low Risk
Small dependency bump and middleware class selection change; main risk is runtime incompatibility if the CSRF middleware class resolution behaves differently across supported Laravel versions.

Overview
Bumps maatwebsite/excel from ^3.1 to ^4.0 to resolve dependency/CI compatibility with newer integrations.

Updates LmsPanelProvider to use Laravel’s newer PreventRequestForgery middleware when available, falling back to VerifyCsrfToken via a small csrfMiddleware() helper for cross-version support.

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