CI/CD workflow fails because of invalid nonce

E.g. [this CircleCI job](https://app.circleci.com/pipelines/github/Shard-Labs/starknet-hardhat-plugin/1143/workflows/fb2416be-449c-4892-ae2e-c86cf9313f4e/jobs/4481).

When testing on alpha-goerli, we are using a funded account (whose private key and address are stored in the CircleCI Shardlabs context).

I believe the nonce error results from the parallel execution of tests while using the same account (simultaneous transactions altering the nonce value). Either that, or someone somewhere is using the account at the same time, and it ain't me.

Possible solutions:
- allow only one test at a time to access the account
- have one account per each parallel job
- have alpha-goerli tests only in one job

Any suggestions?