add validator ETH addresses (ERC20)

[msamsami]

This is a validator for ERC20 Ethereum (ETC) addresses.

[msamsami]

@joe733
Please merge this PR first and merge #277 after that to avoid conflicts.

[nandgator]

@msamsami, please make this PR do one thing. Create another PR to move btc_adderess.py to validators/crypto_addresses.

[msamsami]

@msamsami, please make this PR do one thing. Create another PR to move btc_adderess.py to validators/crypto_addresses.

@joe733
It's done. Here is the correct order for merging the PRs: #276 --> #277 --> #278

[nandgator]

Just one more change.

[nandgator]

@msamsami, I meant the change to be as follows:

# standard
import re

# external
from eth_hash.auto import keccak

# local
from validators.utils import validator

As re is from the standard library, eth_hash.auto.keccak is an external dependency and validators.utils.validator implies a local coupling.

[msamsami]

@joe733 Sorry for the confusion. It's done. 802487f

[nandgator]

Tests have failed. Ref: https://github.com/python-validators/validators/actions/runs/5387269990/jobs/9778426797?pr=276#step:6:182

Also, please use black to format code. Ref: https://github.com/python-validators/validators/actions/runs/5387269990/jobs/9778426797?pr=276#step:6:203

Instead if you simply run tox, all of this could be resolved, locally.

[msamsami]

@joe733 I added backend dependencies of eth-hash and reformatted code using black.

[nandgator]

@msamsami thanks for the PR!