Delete default type for generic param in CredentialsConfig

[kjugi]

Reasoning 💡

By setting the default type for generic like {} we are blocking the inference of type in credentials as the whole typing is intended to do (I think so).

After that change we are able to do the following code in TS with strict mode enabled:

import CredentialsProvider from 'next-auth/providers/credentials';

CredentialsProvider({
  credentials: {
    email: {
      label: 'email',
      type: 'text',
    },
    password: {
      label: 'password',
      type: 'password',
    },
  },
  async authorize() {
    try {
      await fetch('/testing');

      return {
        id: '',
      }
    } catch (err) {
      return null;
    }
  },
}),

I'm aware that marking it as any is never the best solution as I'm doing in the Provider type. But it can get any object shape from us in that case I guess.

Checklist 🧢

• Documentation
• Tests
• Ready to be merged

Affected issues 🎟

Don't know if resolves the following issues so they are just marked as affected.

#2701
#2677

[balazsorban44]

I believe this has been fixed in #2802 by @Thisen