Update benchmarks for OTP 24

[benhaney]

OTP 24 includes a new JIT that should greatly increase the performance of non-NIF encoders like Jason and Poison. It will be interesting to see how much of the performance advantage of Jsonrs shrinks with this update.

[denispeplin]

I've just tried Jsonrs on my app by creating 5000 documents in tests. The results are opposite to what I expected: render took 3 seconds with Jason and 64 seconds with Jsonrs.

[benhaney]

@denispeplin Was that on OTP 24? Can you share the exact benchmark?