cleanup model relationship references

app/Models/Rank.php

@@ -33,7 +33,7 @@ class Rank extends BaseModel
     ];
 
     public function subfleets() {
-        return $this->belongsToMany('App\Models\Subfleet', 'subfleet_rank')
+        return $this->belongsToMany(Subfleet::class, 'subfleet_rank')
                     ->withPivot('acars_pay', 'manual_pay');
     }
 }