Use str_replace instead of Str::replace (#268)

Str::replace introduced in Laravel 8.41.0, we should also support lower versions.

Author: hos3ein

src/Provider/PaymentServiceProvider.php

@@ -5,7 +5,6 @@
 use Shetabit\Multipay\Payment;
 use Illuminate\Support\ServiceProvider;
 use Illuminate\Support\Facades\Blade;
-use Illuminate\Support\Str;
 use Shetabit\Multipay\Request;
 use Shetabit\Payment\Events\InvoicePurchasedEvent;
 use Shetabit\Payment\Events\InvoiceVerifiedEvent;
@@ -67,7 +66,7 @@ public function register()
         // use blade to render redirection form
         Payment::setRedirectionFormViewRenderer(function ($view, $action, $inputs, $method) {
             return Blade::render(
-                Str::replace('</form>', '@csrf</form>', file_get_contents($view)),
+                str_replace('</form>', '@csrf</form>', file_get_contents($view)),
                 [
                     'action' => $action,
                     'inputs' => $inputs,