Hey 👋 Here are my changes.

• There are multiple race condition bugs in sendRequest function. I have implemented two functions for safely incrementing the counters and time with using a mutex lock. (This is still not the proper way to colect values from multiple go routines, best way would be using signal channels for collecting values. But since this is a small project it would be overkill 😃 )
• Here you give a *fasthttp.Response (pointer) to each sendRequest function, thus they all write the response into the same struct :) So, moved the fasthttp.AcquireResponse() call into sendRequest function.
• Refactored the code by fixing coding convention naming, removing unnecessary allocations and type casting.
• Added a timeout parameter. This is a necessary feature because net/http and fasthttp by-default has no timeout on requests, thus it hangs forever.