Update approval-voting-regression-bench (#5504)
The accepted divergence rate of 1/1000 is excessive and leads to false
positives especially after
https://github.com/paritytech/polkadot-sdk/pull/4772 and
https://github.com/paritytech/polkadot-sdk/pull/5042, so let's increase
it to 1/100 since we do have some randomness in the system and there is
no point in being that strict.
Fixes: https://github.com/paritytech/polkadot-sdk/issues/5463
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Signed-off-by: Alexandru Gheorghe <[email protected]>