fix: add disposable methods for TypeScript 5.2 compatibility (#82)

Hi 👋 

First off, thanks for you work on this 🙇 It's making my life a lot
easier 💜

I recently ran into a problem when updating `JSDOM` in my project, where
the return type wasn't compatible any more:

```
error TS2322: Type 'typeof Headers$1' is not assignable to type '{ new
  (init?: HeadersInit | undefined): Headers; prototype: Headers; }'.
    The types returned by 'prototype.entries()' are incompatible between these types.
      Property '[Symbol.dispose]' is missing in type 'IterableIterator<[string, string]>' but
  required in type 'HeadersIterator<[string, string]>'.

  6 globalThis.Headers = HeadersPolyfill;
    ~~~~~~~~~~~~~~~~~~

    node_modules/typescript/lib/lib.esnext.disposable.d.ts:36:5
      36     [Symbol.dispose](): void;
             ~~~~~~~~~~~~~~~~~~~~~~~~~
      '[Symbol.dispose]' is declared here.
```


This PR fixes this and makes makes the polyfill compatible with
TypeScript 5.2+ 🎉

**Background**

TypeScript 5.2 added `[Symbol.dispose]` to iterator types as part of the
[Explicit Resource
Management](https://github.com/tc39/proposal-explicit-resource-management)
proposal.
This property was missing in the polyfills iterators, making them
incompatible with e.g. current JSDOM and TypeScript.

**Change**

This removes the explicit `IterableIterator` return type annotations
from the `entries()`, `keys()` and `values()` generator functions in
favor of the `Generator` type.

---------

Co-authored-by: Artem Zakharchenko <kettanaito@gmail.com>

Author: klappradla

.github/workflows/ci.yml

@@ -12,16 +12,16 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [16, 18]
+        node-version: [20, 22, 24]
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
           token: ${{ secrets.GH_ADMIN_TOKEN }}
 
       - name: Setup Node.js
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
           always-auth: true

.github/workflows/release.yml

@@ -11,13 +11,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
           token: ${{ secrets.GH_ADMIN_TOKEN }}
 
       - name: Setup Node.js
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v4
         with:
           node-version: 18
           always-auth: true

package.json

@@ -29,12 +29,12 @@
   ],
   "devDependencies": {
     "@ossjs/release": "^0.7.3",
-    "@swc/core": "^1.3.84",
-    "@swc/jest": "^0.2.29",
-    "@types/jest": "^28.1.4",
+    "@swc/core": "^1.15.18",
+    "@swc/jest": "^0.2.39",
+    "@types/jest": "^30.0.0",
     "@types/set-cookie-parser": "^2.4.3",
-    "jest": "^28.1.2",
-    "jest-environment-jsdom": "^28.1.2",
+    "jest": "^30.2.0",
+    "jest-environment-jsdom": "^30.2.0",
     "rimraf": "^3.0.2",
     "set-cookie-parser": "^2.6.0",
     "tsup": "^7.2.0",

src/Headers.test.ts

@@ -131,6 +131,13 @@ describe('.keys()', () => {
     headers.append('Set-Cookie', 'b=2')
     expect(Array.from(headers.keys())).toEqual(['set-cookie', 'set-cookie'])
   })
+
+  if (process.version.startsWith('22.')) {
+    it('returns an iterator with [Symbol.dispose] defined', () => {
+      const headers = new Headers()
+      expect(headers.keys()[Symbol.dispose]).toBeInstanceOf(Function)
+    })
+  }
 })
 
 describe('.values()', () => {
@@ -174,6 +181,13 @@ describe('.values()', () => {
     headers.append('Set-Cookie', 'b=2')
     expect(Array.from(headers.values())).toEqual(['a=1', 'b=2'])
   })
+
+  if (process.version.startsWith('22.')) {
+    it('returns an iterator with [Symbol.dispose] defined', () => {
+      const headers = new Headers()
+      expect(headers.values()[Symbol.dispose]).toBeInstanceOf(Function)
+    })
+  }
 })
 
 describe('.entries()', () => {
@@ -228,6 +242,13 @@ describe('.entries()', () => {
       ['set-cookie', 'b=2'],
     ])
   })
+
+  if (process.version.startsWith('22.')) {
+    it('returns an iterator with [Symbol.dispose] defined', () => {
+      const headers = new Headers()
+      expect(headers.entries()[Symbol.dispose]).toBeInstanceOf(Function)
+    })
+  }
 })
 
 describe('.has()', () => {

src/Headers.ts

@@ -58,19 +58,19 @@ export class Headers {
     return this.entries()
   }
 
-  *keys(): IterableIterator<string> {
+  *keys(): Generator<string> {
     for (const [name] of this.entries()) {
       yield name
     }
   }
 
-  *values(): IterableIterator<string> {
+  *values(): Generator<string> {
     for (const [, value] of this.entries()) {
       yield value
     }
   }
 
-  *entries(): IterableIterator<[string, string]> {
+  *entries(): Generator<[string, string]> {
     // https://fetch.spec.whatwg.org/#concept-header-list-sort-and-combine
     let sortedKeys = Object.keys(this[NORMALIZED_HEADERS]).sort((a, b) =>
       a.localeCompare(b)