Replace node-fetch to undici

[katayama8000]

Internal refactoring: Replace node-fetch with undici

Motivation
The primary objective of this refactoring is to modernize our HTTP request stack and align the library with the evolving Node.js ecosystem standards.

1. Alignment with Node.js Standards: undici is the high-performance HTTP client that powers the native fetch implementation in modern Node.js versions (v18+). By migrating to undici, we transition from a third-party polyfill (node-fetch) to the platform's underlying standard, ensuring better long-term maintainability and performance.
2. Dependency Simplification: While this swaps one dependency for another, undici provides a more "native" and foundational choice for the Node.js runtime. Furthermore, this change allowed us to remove msw from our development dependencies by leveraging undici's built-in mocking capabilities.

[katayama8000]

#71

[katayama8000]

@douglowder Could you review this?

[nicknovitski]

I've fixed our test workflow to run on pull requests, so if you update your branch, all those required statuses will pass:

Sorry that we didn't have that set up already, thanks again for the contribution!

[douglowder]

See inline comments

[joaoschaab]

Any updates on this one?

[katayama8000]

@joaoschaab no.

[katayama8000]

@douglowder @nicknovitski @ide
After some time, I have successfully removed node-fetch.
Can you review this?

[vonovak]

Thanks for the PR!
I have taken a quick look, I'll still need to take a better look later.

For now please:

• kindly accept the suggestion, it simplifies the code a bit
• fill out the PR description - what's the motivation for the change, why so many changes to the test suite were needed, and anything else that comes to your mind. Anybody from the community who visits the PR should be able to get read some reasoning on this.
  Thank you!

[katayama8000]

Thanks for the PR! I have taken a quick look, I'll still need to take a better look later.

For now please:

• kindly accept the suggestion, it simplifies the code a bit
• fill out the PR description - what's the motivation for the change, why so many changes to the test suite were needed, and anything else that comes to your mind. Anybody from the community who visits the PR should be able to get read some reasoning on this.
  Thank you!

#116 (comment)

I filled out the PR description. Could you review it again? @vonovak

[nicknovitski]

I understand the need for the changes to the tests: msw doesn't work with an explicitly imported undici, but undici has a built-in mocking feature.

On the subject of documentation, this would be a breaking change, since the agent option now is an undici agent, not an http agent.

[katayama8000]

I understand the need for the changes to the tests: msw doesn't work with an explicitly imported undici, but undici has a built-in mocking feature.

On the subject of documentation, this would be a breaking change, since the agent option now is an undici agent, not an http agent.

@nicknovitski
Thanks for the review.
Is there any docmentation I should fix or Does this mean we need a major version bump?