Verify needs to honor API rate limits

[mwawrusch]

Describe the bug
Running into API limits with basescan (5 per second) when verifying contracts while some contracts have already been deployed before. E.g. we get an immediate repsonse, and doing this 6 times triggers a 403

To reproduce:

• deploy and verify say 10 contracts. Then add another contract and deploy. Then verify. This loops through all the previously verified contracts and checks if they have been deployed which consumes API request at too fast a rate.

Solution

• just sleep for 400ms between each API call. Or listen for 403 errors and back off.

[mwawrusch]

Never mind, looks like there is a VERY WELL hidden --sleep 500 option.