Don't print Etherscan api key in logs

[iirekm]

Currently ityfuzz produces logs like:

INFO fetching abi from https://api.bscscan.com/api?module=contract&action=getabi&address=0x84...&format=json&apikey=C7...

This is potential security issue e.g.:

• if someone uses a paid version of Etherscan and this key leaks via logs so someone else can use the key for free
• if someone does a leaked key to commit a crypto crime and investigation leads to other, innocent person

Users generally don't expect keys in logs. It should be e.g. replaced with ***secret***.