Unrestricted php file upload fix (#681)

https://huntr.dev/bounties/d7453360-baca-4e56-985f-481275fa38db/

app/Http/Requests/AvatarRequest.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace Crater\Http\Requests;
+
+use Crater\Rules\Base64Mime;
+use Illuminate\Foundation\Http\FormRequest;
+
+class AvatarRequest extends FormRequest
+{
+    /**
+     * Determine if the user is authorized to make this request.
+     *
+     * @return bool
+     */
+    public function authorize()
+    {
+        return true;
+    }
+
+    /**
+     * Get the validation rules that apply to the request.
+     *
+     * @return array
+     */
+    public function rules()
+    {
+        return [
+            'admin_avatar' => [
+                'nullable',
+                'file',
+                'mimes:gif,jpg,png',
+                'max:20000'
+            ],
+            'avatar' => [
+                'nullable',
+                new Base64Mime(['gif', 'jpg', 'png'])
+            ]
+        ];
+    }
+}