Add jsons benchmark

[brodmo]

Not sure if I should have created an issue first but this is pretty straightforward. Please review

[brodmo]

My benchmark results are somewhat different from those in the docs:

Package	Version	Relative Performance	Mean validation time
attrs + cattrs	21.4.0		21.3μs
pydantic	1.9.0	1.2x slower	24.5μs
valideer	0.4.2	1.4x slower	28.9μs
marshmallow	3.14.1	3.3x slower	69.5μs
voluptuous	0.12.2	3.3x slower	69.9μs
trafaret	2.1.0	3.6x slower	77.1μs
jsons	1.6.1	10.9x slower	231.4μs
schematics	2.1.1	11.9x slower	253.2μs
django-rest-framework	3.13.1	14.5x slower	308.6μs
cerberus	1.3.4	27.8x slower	590.9μs

I've refrained from pushing them for this reason.

[samuelcolvin]

Sorry but I can't accept this. See #1810 (comment)

I'll remove the benchmarks soon, they're wasting peoples time (like this, I'm so sorry). They need a lot of work and that's outside the bounds of pydantic.

[brodmo]

I see, that's unfortunate. Looking further into it I think wyfo makes a lot of good points here #3264 and the benchmarks really ought to be removed, glad you agree. I originally became interested in the benchmarks because pydantic often didn't behave the way I wanted it to and its supposed performance edge and in particular the benchmarks were pointed to as the reason why, see #1157 (comment). I feel a little misled but the comment is admittedly pretty old and a lot of things seem to have changed since then (though the benchmarks page doesn't reflect that unfortunately)