Prepare Solana Authentication

curl --request POST \
  --url https://alerts-api.dial.to/v2/auth/solana/prepare \
  --header 'Content-Type: application/json' \
  --data '{
  "walletAddress": "6CxnSjtasq5Tzwb4b93AhLofXtiDvMpQ2vTkWdSZqTH7"
}'

{
  "message": "Sign this message to authenticate. Nonce: 1638471298347"
}