Cannot create enum dynamically with f-string

* **What is the current behavior?**

This does not work.

```
distances_km = [1, 2, 5, 10, 20, 40, 60, 80, 100, 250, 500]
distances_with_enum_labels = [
(f'kilometre_{d}', d)
for d in distances_km
]
DistanceWithin = graphene.Enum(
'Distance Within', [(d for d in distances_with_enum_labels])
```

Error - AssertionError: Names must match /^[_a-zA-Z][_a-zA-Z0-9]*$/ but "Distance Within" does not

* **What is the expected behavior?**

It should allow this.