Reversing priority of token and endpoint environment variables

[millette]

Started as a line comment but let's make it an issue and fix/close it.

The readme says clearly:

Can be overridden globally with the GITHUB_TOKEN environment variable.

Same for the endpoint.

Not sure what the logic was, but I think it would be preferable to use the environment variables only when no applicable argument is passed. An application could have a default token (the env.) but for whatever reason use another token on specific calls.

The module, readme and test would have to be updated. It could be considered a major change since it's reversing its meaning.

[sindresorhus]

Makes sense to me.

@floatdrop @SamVerschueren Thoughts?

[SamVerschueren]

Makes sense to me as well. The options object has higher priority then other global settings.

[floatdrop]

Yep, options should not be overridden by globals.

[sindresorhus]

Alright. Let's do it. PR welcome.