Fix error causing inability to save variables.

app/Http/Requests/Admin/Egg/EggVariableFormRequest.php

@@ -18,7 +18,6 @@ class EggVariableFormRequest extends AdminFormRequest
             'name' => 'required|string|min:1|max:255',
             'description' => 'sometimes|nullable|string',
             'env_variable' => 'required|regex:/^[\w]{1,255}$/|notIn:' . EggVariable::RESERVED_ENV_NAMES,
-            'default_value' => 'nullable|string',
             'options' => 'sometimes|required|array',
             'rules' => 'bail|required|string',
         ];