bugfix: Fix the types of AbortSignal

node-fetch#1287 has the unintended consequence of breaking the types of `AbortSignal`. This fixes it.

The [`AbortSignal` definition from `node-fetch`](https://github.com/node-fetch/node-fetch/blob/bcfb71c7d10da252280d13818daab6925e12c368/%40types/index.d.ts#L14-L19) is different from the [node's one](https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/node/globals.d.ts#L59-L65).

This wasn't an issue before because the dom types were imported and were extending the nodejs types with the event listener methods, but that's not the case anymore.

The issue can be reproduce with the following steps:
```
mkdir test && cd test
npm i node-fetch @types/node typescript
touch test.ts
touch tsconfig.json
```

with the `tsconfig.json`:
```json
{
  "include": ["test.ts"],
  "compilerOptions": {
    "lib": ["es2022"],
    "module": "es2022",
    "target": "es2022",
    "skipLibCheck": true,
    "moduleResolution": "node"
  }
}
```

and the test.ts (taken from the README):
```ts
import fetch, { AbortError } from "node-fetch";

const controller = new AbortController();
const timeout = setTimeout(() => {
  controller.abort();
}, 150);

try {
  const response = await fetch("https://example.com", {
    signal: controller.signal,
  });
  const data = await response.json();
} catch (error) {
  if (error instanceof AbortError) {
    console.log("request was aborted");
  }
} finally {
  clearTimeout(timeout);
}
```

Running `npx tsc --project ./tsconfig.json` will show
```
test.ts:10:5 - error TS2739: Type 'AbortSignal' is missing the following properties from type 'AbortSignal': addEventListener, removeEventListener

10     signal: controller.signal,
       ~~~~~~

  node_modules/node-fetch/@types/index.d.ts:91:2
    91  signal?: AbortSignal | null;
        ~~~~~~
    The expected type comes from property 'signal' which is declared here on type 'RequestInit'


Found 1 error in test.ts:10
```

@types/index.d.ts

@@ -13,9 +13,6 @@ import {
 
 type AbortSignal = {
 	readonly aborted: boolean;
-
-	addEventListener: (type: 'abort', listener: (this: AbortSignal) => void) => void;
-	removeEventListener: (type: 'abort', listener: (this: AbortSignal) => void) => void;
 };
 
 export type HeadersInit = Headers | Record<string, string> | Iterable<readonly [string, string]> | Iterable<Iterable<string>>;