Omitting a key does not does not work on the Config type

[Quintisimo]

Environments:

• Prettier Version: 3.2.5
• Running Prettier via: Node API
• Runtime: Node.js v20.12.2
• Operating System: macOS
• Prettier plugins (if any): n/a

Steps to reproduce:

1. Import the Config type in a typescript file
2. Type to omit the plugins property on the Config

Expected behaviour:
Returns the Config type without the plugins property

Actual behavior:
Returns { [x: string]: unknown; [x: number]: unknown; }