Use app helper instead of resolve.

Fix #2351.

Author: yajra

src/Services/DataTable.php

@@ -176,7 +176,7 @@ public function render($view, $data = [], $mergeData = [])
      */
     public function request()
     {
-        return $this->request ?: $this->request = resolve('datatables.request');
+        return $this->request ?: $this->request = app('datatables.request');
     }
 
     /**
@@ -520,7 +520,7 @@ public function pdf()
     public function snappyPdf()
     {
         /** @var \Barryvdh\Snappy\PdfWrapper $snappy */
-        $snappy      = resolve('snappy.pdf.wrapper');
+        $snappy      = app('snappy.pdf.wrapper');
         $options     = config('datatables-buttons.snappy.options');
         $orientation = config('datatables-buttons.snappy.orientation');