Loading settings.toml file yieds generic error

[brentru]

When loading the toml file, we should try/except and give a specific error message that tells the user about the settings.toml file including what it is and its location:

https://github.com/adafruit/Adafruit_CircuitPython_Fake_BME280/blob/main/fake_bme280/basic.py#L79

[tyeth]

I stumbled into this one today. No settings.toml file breaking tests in WipperSnapper Python which relies on .env instead of settings.toml

Feels like we should actually test it's presence as mentioned, and maybe instead rely on the common methods like OS.GetEnv which provides cross platform support for variables.

Potentially we want to match WipperSnapper Python which depends on DotEnv to load variables instead, along with it not overloading environment variables by default:
.venv/Lib/site-packages/dotenv/main.py#L387

As this is fake data we probably want zero dependencies. Maybe two fake BME280 classes, one with random data, and another representing local weather from openweather, or just a constructor arg to turn off the requirement for openweather.