Remaining Beacon Block Root Tests EIP-4788

[spencer-tb]

🧪 Remaining Test Cases

- [x] `test_beacon_root_precompile_calls_with_balance`: Call the pre-compile where the origin tx contains some wei which is used within the call.
- [x] `test_beacon_root_precompile_withdrawal`: Perform a withdrawal to the pre-compile address.
- [x] `test_beacon_root_precompile_with_blobs`: Perform multiple precompile calls with blob txs.
- [x] Update & refactor tests using a `spec.py` file following: #203

[danceratopz]

@spencer-tb I think you can enjoy ticking some boxes!