Explicit file extensions required for `nodenext` for type declaration files

[nickdnk]

Hello

I'm trying to use this project with react-email, and I compile it with tsc using:
tsc index.ts --target esnext --moduleResolution nodenext --module nodenext --jsx react-jsx

Importing this project like this in index.ts:

import {createMimeMessage, Mailbox, MailboxAddrObject} from "mimetext";

But it complains that file extensions are missing in this configuration:

node_modules/mimetext/dist/MIMEMessageContent.d.ts:1:41 - error TS2834: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Consider adding an extension to the import path.

1 import type { EnvironmentContext } from './MIMEMessage';
                                          ~~~~~~~~~~~~~~~

node_modules/mimetext/dist/MIMEMessageContent.d.ts:2:30 - error TS2834: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Consider adding an extension to the import path.

2 import type { Mailbox } from './Mailbox';
                               ~~~~~~~~~~~

node_modules/mimetext/dist/MIMEMessageHeader.d.ts:1:41 - error TS2834: Relative import paths need explicit file extensions in ECMAScript imports when '--moduleResolution' is 'node16' or 'nodenext'. Consider adding an extension to the import path.

1 import type { EnvironmentContext } from "./MIMEMessage";
                                          ~~~~~~~~~~~~~~~

It is fixed by simply adding .d.ts to these types, i.e:

import type { EnvironmentContext } from './MIMEMessage.d.ts';

nodenext is required in order to compile react-email, so I cannot omit this. It seems you can also just add .js, but I'm unsure in which places this would cause a problem. It just needs any of the valid file extensions, it seems.