Currency not updated after updates from external services

[AlexITC]

Currency not updated after updates from external services

Expected behavior

If an external service (like Coinmarketcap) updates the details for a currency, they should be updated in our database.

Actual behavior

The application fails to update the values and it keeps sending alerts about the non-updated currency.

Steps to reproduce the behavior

1. Seed the database
2. Choose a currency and update its currency_name
3. The issue will occur when the currency seeder task run.

One simple way would be to change the insert to upsert.