eth: update solc and abigen workflow

[chappjc]

Wtih go-ethereum 1.10.18, abigen no longer has compiler invocation support, and we must use solc directly.

Resolves #1625

[martonp]

Works well.

[JoeGruffins]

I have changes when doing ./updatecontract.sh 0

I'm using:

$ solc --version
solc, the solidity compiler commandline interface
Version: 0.8.6+commit.11564f7e.Linux.g++
$ abigen --version
abigen version 1.10.2-stable-97d11b01

Maybe can add something about the versions in the README? Also we have a testnet address now you could add.

[chappjc]

I have changes when doing

Changes other than what's in the PR? To Bin or other parts of contract.go?

$  solc --version
solc, the solidity compiler commandline interface
Version: 0.8.6+commit.11564f7e.Linux.g++
$  abigen --version
abigen version 1.10.18-stable

Running an old abigen?

[JoeGruffins]

Running an old abigen?

Yes. No changes after updating to 1.10.18-stable