Update index.d.ts

[ghost]

Is there any harm in doing this? So I don't have to do nested templates like:

    this.log(`Inbox contains ${green(`${inbox.files.length}`)} reports:`);
    this.log(`Valid:   ${green(`${inbox.accepted.length}`)}`);
    this.log(`Invalid: ${green(`${inbox.rejected.length}`)}`);

and just do...

    this.log(`Inbox contains ${green(inbox.files.length)} reports:`);
    this.log(`Valid:   ${green(inbox.accepted.length)}`);
    this.log(`Invalid: ${green(inbox.rejected.length)}`);

[doowb]

Hi @cncshaggy ... sorry for not responding sooner and thanks for the PR!

Since the input is technically "cast" to a string here, I believe this should be any. (Also, null and undefined are valid inputs, which return an empty string)

If you'd like to update that to any, I'll get this merged.