Fix GateCollector (+5.4 syntax)

Fixes barryvdh#439

Author: barryvdh

src/LaravelDebugbar.php

@@ -365,7 +365,7 @@ function ($query, $bindings = null, $time = null, $connectionName = null) use ($
 
         if ($this->shouldCollect('gate', false)) {
             try {
-                $gateCollector = $this->app->make(GateCollector::class);
+                $gateCollector = $this->app->make('Barryvdh\Debugbar\DataCollector\GateCollector');
                 $this->addCollector($gateCollector);
             } catch (\Exception $e){
                 // No Gate collector