[BUG] Unable to read mnemonic phrase from .env file to start Relayer

[ltfschoen]

In the Relayer documentation it says that you can provide a mnemonic phrase instead of the private key. But it doesn't work.

In this part of the Relayer code it even says only private key is supported https://github.com/webb-tools/relayer/blob/develop/crates/relayer-config/src/lib.rs#L110

Expected Behavior

It should support use of a mnemonic phrase if the documentation says it is supported.

Current Behavior

It gives the following error if you provide a mnemonic phrase when you run ~/.webb/webb-relayer -vvv to run the Relayer

Error: Config parse error: evm.goerli.private-key: Invalid character 'o' at position 1
 expected a 66 chars string (including the 0x prefix) but found 157 char

Possible Solution

Update this documentation to state that mnemonic phrases are not supported if they are not supported, or otherwise support reading a mnemonic phrase instead of just a private key.

Steps to Reproduce

Follow the steps here and try using a mnemonic phrase instead of a private key https://github.com/webb-tools/webb-docs/blob/main/pages/docs/ecosystem-roles/relayer/running-relayer/quick-start.mdx#L109

Log output

Log Output

{"timestamp":"2024-02-29T00:27:40.210978Z","level":"ERROR","message":"evm.goerli.private-key: Invalid character 'o' at position 1\n expected a 66 chars string (including the 0x prefix) but found 157 char","target":"webb_relayer_config::utils"}
Error: Config parse error: evm.goerli.private-key: Invalid character 'o' at position 1
expected a 66 chars string (including the 0x prefix) but found 157 char