Fix formatting issues with toml.dump

[relic-se]

I found that I would encounter issues with os.getenv and supervisor.get_setting when updating settings.toml with toml.dump. Specifically, it would expect the following:

• Strings to be wrapped in double quotes rather than single quotes
• Boolean values to be lowercase (ie: true and false rather than True and False)

This update changes the value formatting within toml.dumps to fix this error.

Example Code

# boot.py
import storage
storage.remount("/", False)

# code.py
import supervisor
import toml

data = {
    "teststr": "Hello world!",
    "testbool": True
}
with open("/settings.toml", "w") as f:
    toml.dump(data, f)
print((
    supervisor.get_setting("teststr"),
    supervisor.get_setting("testbool")
))
# prints "('Hello world!', True)"

[elpekenin]

Could reproduce the issues and confirm these changes fix them!

Just a couple of nitpick suggestions about the writing of the code, while keeping its behaviour

Thanks for your contribution

[relic-se]

@elpekenin A-okay with your suggestions. 👍

Should be good to go now.