fix drivers

src/Illuminate/Concurrency/ForkDriver.php

@@ -3,11 +3,12 @@
 namespace Illuminate\Concurrency;
 
 use Closure;
+use Illuminate\Contracts\Concurrency\Driver;
 use Illuminate\Foundation\Defer\DeferredCallback;
 use Illuminate\Support\Arr;
 use Spatie\Fork\Fork;
 
-class ForkDriver
+class ForkDriver implements Driver
 {
     /**
      * Run the given tasks concurrently and return an array containing the results.

src/Illuminate/Concurrency/ProcessDriver.php

@@ -3,14 +3,15 @@
 namespace Illuminate\Concurrency;
 
 use Closure;
+use Illuminate\Contracts\Concurrency\Driver;
 use Illuminate\Foundation\Defer\DeferredCallback;
 use Illuminate\Process\Factory as ProcessFactory;
 use Illuminate\Process\Pool;
 use Illuminate\Support\Arr;
 use Laravel\SerializableClosure\SerializableClosure;
 use Symfony\Component\Process\PhpExecutableFinder;
 
-class ProcessDriver
+class ProcessDriver implements Driver
 {
     /**
      * Create a new process based concurrency driver.

src/Illuminate/Concurrency/SyncDriver.php

@@ -3,10 +3,11 @@
 namespace Illuminate\Concurrency;
 
 use Closure;
+use Illuminate\Contracts\Concurrency\Driver;
 use Illuminate\Foundation\Defer\DeferredCallback;
 use Illuminate\Support\Arr;
 
-class SyncDriver
+class SyncDriver implements Driver
 {
     /**
      * Run the given tasks concurrently and return an array containing the results.

src/Illuminate/Contracts/Concurrency/Driver.php

@@ -3,6 +3,7 @@
 namespace Illuminate\Contracts\Concurrency;
 
 use Closure;
+use Illuminate\Foundation\Defer\DeferredCallback;
 
 interface Driver
 {
@@ -12,7 +13,7 @@ interface Driver
     public function run(Closure|array $tasks): array;
 
     /**
-     * Start the given tasks in the background.
+     * Defer the execution of the given tasks.
      */
-    public function background(Closure|array $tasks): void;
+    public function defer(Closure|array $tasks): DeferredCallback;
 }