Use env to find bash in build.sh script to support FreeBSD (#87)

Co-authored-by: Vedran Miletić <vedran.miletic@rxtx.tech>

Author: vedranmiletic

build.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 #building trantor
 function build_trantor() {