validation issue

[banteg]

there are several validation issues with tokenlistooor-produced token list:

1. instead of omitting the optional logoURI where it doesn't exist, the script populates the list with "logoURI": "" which is not a valid uri
2. the timestamp format must be in iso format. instead of "timestamp": "08/04/2024 14:16:52" it should say 2024-08-04T14:16:52Z or 2024-08-04T14:16:52+00:00

the official json schema can be found here https://github.com/Uniswap/token-lists/blob/main/src/tokenlist.schema.json

[banteg]

meanwhile relaxed the checks in ape ApeWorX/py-tokenlists#39

[Majorfi]

Timestamp has been updated, we are checking for the logoURI