Consider Using F-Strings

There are a few places in this library that pylint reports we should consider using f-strings instead of string formatting.

- `adafruit_dash_display.py:262:14: C0209: Formatting a regular string which could be a f-string `
- `adafruit_dash_display.py:271:14: C0209: Formatting a regular string which could be a f-string `