future-public: add kline request

src/Requests/FutureKLineRequestContract.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Msr\LaravelBitunixApi\Requests;
+
+use Psr\Http\Message\ResponseInterface;
+
+interface FutureKLineRequestContract
+{
+    /**
+     * @param string $symbol
+     * @param string $interval
+     * @param int $limit
+     * @param int|null $startTime
+     * @param int|null $endTime
+     * @param string $type
+     * @return ResponseInterface
+     *
+     * interval could be: 1m 5m 15m 30m 1h 2h 4h 6h 8h 12h 1d 3d 1w 1M
+     * limit: max is 200
+     * startTime : milliseconds format
+     * endTime : milliseconds format
+     * type could be: LAST_PRICE, MARK_PRICE
+     */
+    public function getFutureKline(string $symbol,
+                             string $interval,
+                             int    $limit = 100,
+                             ?int   $startTime = null,
+                             ?int   $endTime = null,
+                             string $type = 'LAST_PRICE'): ResponseInterface;
+}