Make Currencies comparable

Hi there!
Out of curiosity, was there any decision behind not implementing the `__eq__` method inside the Currency class?

In my - maybe naive - understanding, it would make sense to be able to compare Currency objects like so:
``
Currency('USD') == Currency('USD')
``
which as of now returns False, as the object's pointers are compared, not the values.

My workaround for this is as follows (python 3.10 code, for python < 3.10 the `__ne__` method also needs to be implemented)
```python
class ComparableCurrency(Currency):
def __eq__(self, other):
return isinstance(other, Currency) and self.get_money_currency() == other.get_money_currency()
```

If for any reason, it doesn't make sense to compare two Currencies with each other, or the implementation on `currency.get_money_currency()` is too simple, I would really like to undestand the problems with that.