future-public: add kline request

tests/KLineTest.php

@@ -0,0 +1,13 @@
+<?php
+
+use Msr\LaravelBitunixApi\Requests\FutureKLineRequestContract;
+
+it('check kline request response code', function () {
+
+    $bootedClass = app(FutureKLineRequestContract::class);
+    $response = $bootedClass->getFutureKline('BTCUSDT', '1h', 100, now()->subHours(6)->milliseconds, now()->milliseconds);
+    expect($response->getStatusCode())
+        ->toBe(200)
+        ->and(json_decode($response->getBody()->getContents()))
+        ->toHaveKeys(['code', 'data', 'msg']);
+});