Default wallet path

[ALFecki]

We are experiencing an issue with the default wallet path in our development environment. The problem arises when an explicit argument is not provided; the neuron crashes with an error message similar to the following:
KeyFileError: Keyfile at: /home/ubuntu/~/.bittensor/wallets/miner/hotkeys/default does not exist.

The following line needs to be fixed:

btwallet/src/wallet.rs

Line 193 in f41da22

.unwrap_or_else(|_| format!("~/{}", BT_WALLET_PATH.to_string()));