Fix dependencies in order to merge PMAT 0.48.0

[gabrielfior]

When upgrading the dependecy on PMAT to 0.48.0, dependency issues arise:

Because no versions of open-aea-ledger-ethereum match >1.53.0,<1.54.0 || >1.54.0,<1.55.0 || >1.55.0,<2.0.0
 and open-aea-ledger-ethereum (1.53.0) depends on eth-account (>=0.8.0,<0.9.0), open-aea-ledger-ethereum (>=1.53.0,<1.54.0 || >1.54.0,<1.55.0 || >1.55.0,<2.0.0) requires eth-account (>=0.8.0,<0.9.0).

mostly because of the eth-ape new dependency, which upgraded eth-account on PMAT, making it not compatible with mech-client.

Here we should investigate options to make the dependencies become compatible again, namely

• Downgrade ape (not possible -> 6.15 tag would work w.r.t. eth-account, but pydantic < 2 breaks things)
• Upgrade open-aea eth_account to >= 0.10.0 (upgrade https://github.com/valory-xyz/open-aea/blob/776bcaab67b3e5ec7629c9e2b6c603d8077c640b/plugins/aea-ledger-ethereum/setup.py#L47) - opened an issue on their repo
• Create new mech-client repo with fewer dependencies