[fix] GethPOAMiddleware on Polygon networks with anvil fork

[kx9x]

What I did

On Polygon networks, anvil in forked development mode doesn't throw ExtraDataLengthError on the first block. So, I changed the GethPOAMiddleware to try both the first block and latest block. This is similar to apeworx implementation here:
ApeWorX/ape-hardhat#133

Related issue: #1762

How I did it

How to verify it

ran anvil locally

anvil --accounts 10 --fork-url <REDACTED> --gas-limit 12000000 --port 8545 --chain-id 137 &

connect web to anvil

web3.connect('http://localhost:8545')

verify we hit the exception on latest block, but not on first block

>>> try:
...     web3.eth.get_block("latest")
... except Exception as e:
...     print(type(e))
... 
eth_getBlockByNumber
<class 'web3.exceptions.ExtraDataLengthError'>

>>> try:
...     web3.eth.get_block(0)
... except Exception as e:
...     print(type(e))
... 
eth_getBlockByNumber
AttributeDict({'hash': HexBytes('0xa9c28ce2141b56c474f1dc504bee9b01eb1bd7d1a507580d5519d4437a97de1b'), 'parentHash': HexBytes('0x0000000000000000000000000000000000000000000000000000000000000000'), 'sha3Uncles': HexBytes('0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347'), 'miner': '0x0000000000000000000000000000000000000000', 'stateRoot': HexBytes('0x654f28d19b44239d1012f27038f1f71b3d4465dc415a382fb2b7009cba1527c8'), 'transactionsRoot': HexBytes('0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421'), 'receiptsRoot': HexBytes('0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421'), 'logsBloom': HexBytes('0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'), 'difficulty': 1, 'number': 0, 'gasLimit': 10000000, 'gasUsed': 0, 'timestamp': 1590824836, 'totalDifficulty': 1, 'extraData': HexBytes('0x'), 'mixHash': HexBytes('0x0000000000000000000000000000000000000000000000000000000000000000'), 'nonce': HexBytes('0x0000000000000000'), 'uncles': [], 'transactions': [], 'size': 508})

Checklist

• [X ] I have confirmed that my PR passes all linting checks
• I have included test cases
• [N/A] I have updated the documentation
• I have added an entry to the changelog