Prevent abstract jobs from being included in the list

src/Jobs/JobInspector.php

@@ -103,6 +103,11 @@ class JobInspector
             return null;
         }
 
+        $reflect = new \ReflectionClass($classPath);
+        if ($reflect->isAbstract()) {
+            return null;
+        }
+
         // Build the class name and namespace
         return [
             'sprinkle' => $sprinkleName,