add a benchmark for JSON where errors are not generated #1008

Job	Run time
Test (stable)	43s
Bench	41s
Test minimal rust version	20s
Test (beta)	46s
Coverage	49s
Test (nightly)	48s
Test (1.65.0)	53s
Build documentation	1m 6s
Test (stable, --features "std")	42s
Check formatting	13s
Test (stable, --no-default-features)	38s
Test (stable, --no-default-features --features "alloc")	45s
Test (nightly, --no-default-features)	34s
Test (nightly, --no-default-features --features "alloc")	45s
	9m 43s

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