Fix tests (#77)

Fixes two tests failing now due to empty api key. Added common logic
from lib.rs to load api keys from env vars.

Ignored supposed to fail gas estimate test since now Etherscan is
returning success result with gas even equal to 0.

There's another failing test for fanthom abi query since there's no api
key specified.
We need fantomscan api key or otherwise should use other network to
test.

Author: igorline

crates/block-explorers/test-data/cache/abi/0x00000000219ab540356cbb839cbe05303d7705fa.json

@@ -1 +1 @@
-{"expiry":1713286751,"data":[{"type":"constructor","inputs":[],"stateMutability":"nonpayable"},{"type":"function","name":"deposit","inputs":[{"name":"pubkey","type":"bytes","internalType":"bytes"},{"name":"withdrawal_credentials","type":"bytes","internalType":"bytes"},{"name":"signature","type":"bytes","internalType":"bytes"},{"name":"deposit_data_root","type":"bytes32","internalType":"bytes32"}],"outputs":[],"stateMutability":"payable"},{"type":"function","name":"get_deposit_count","inputs":[],"outputs":[{"name":"","type":"bytes","internalType":"bytes"}],"stateMutability":"view"},{"type":"function","name":"get_deposit_root","inputs":[],"outputs":[{"name":"","type":"bytes32","internalType":"bytes32"}],"stateMutability":"view"},{"type":"function","name":"supportsInterface","inputs":[{"name":"interfaceId","type":"bytes4","internalType":"bytes4"}],"outputs":[{"name":"","type":"bool","internalType":"bool"}],"stateMutability":"pure"},{"type":"event","name":"DepositEvent","inputs":[{"name":"pubkey","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"withdrawal_credentials","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"amount","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"signature","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"index","type":"bytes","indexed":false,"internalType":"bytes"}],"anonymous":false}]}
+{"expiry":1741879991,"data":[{"type":"constructor","inputs":[],"stateMutability":"nonpayable"},{"type":"function","name":"deposit","inputs":[{"name":"pubkey","type":"bytes","internalType":"bytes"},{"name":"withdrawal_credentials","type":"bytes","internalType":"bytes"},{"name":"signature","type":"bytes","internalType":"bytes"},{"name":"deposit_data_root","type":"bytes32","internalType":"bytes32"}],"outputs":[],"stateMutability":"payable"},{"type":"function","name":"get_deposit_count","inputs":[],"outputs":[{"name":"","type":"bytes","internalType":"bytes"}],"stateMutability":"view"},{"type":"function","name":"get_deposit_root","inputs":[],"outputs":[{"name":"","type":"bytes32","internalType":"bytes32"}],"stateMutability":"view"},{"type":"function","name":"supportsInterface","inputs":[{"name":"interfaceId","type":"bytes4","internalType":"bytes4"}],"outputs":[{"name":"","type":"bool","internalType":"bool"}],"stateMutability":"pure"},{"type":"event","name":"DepositEvent","inputs":[{"name":"pubkey","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"withdrawal_credentials","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"amount","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"signature","type":"bytes","indexed":false,"internalType":"bytes"},{"name":"index","type":"bytes","indexed":false,"internalType":"bytes"}],"anonymous":false}]}