Fix Workers AI local mode fetcher not returning headers to client worker

[G4brym]

What this PR solves / how to test

Fixes Workers AI local mode fetcher not returning headers to client worker

Author has addressed the following

• Tests
  • [ ] Included
  • [x] Not necessary because:
• Changeset (Changeset guidelines)
  • [ ] Included
  • [x] Not necessary because:
• Public documentation
  • [ ] Cloudflare docs PR(s): https://github.com/cloudflare/cloudflare-docs/pull/...
  • [x] Not necessary because: this is a small fix

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: ee2da8cf1f60232bd57378839e3bf3a3543c20db

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
wrangler	Patch
@cloudflare/vitest-pool-workers	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions[bot]]

A wrangler prerelease is available for testing. You can install this latest build in your project with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8138819560/npm-package-wrangler-5138

You can reference the automatically updated head of this PR with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/5138/npm-package-wrangler-5138

Or you can use npx with this latest build directly:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8138819560/npm-package-wrangler-5138 dev path/to/script.js

Additional artifacts:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8138819560/npm-package-create-cloudflare-5138 --no-auto-update

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8138819560/npm-package-cloudflare-kv-asset-handler-5138

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8138819560/npm-package-miniflare-5138

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8138819560/npm-package-cloudflare-pages-shared-5138

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/8138819560/npm-package-cloudflare-vitest-pool-workers-5138

Note that these links will no longer work once the GitHub Actions artifact expires.

---

[email protected] includes the following runtime dependencies:

Package	Constraint	Resolved
miniflare	workspace:*	3.20240223.0
workerd	1.20240223.1	1.20240223.1
workerd --version	1.20240223.1	2024-02-23

Please ensure constraints are pinned, and miniflare/workerd minor versions match.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 20.00000% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 70.33%. Comparing base (9d1d11c) to head (ee2da8c). Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5138   +/-   ##
=======================================
  Coverage   70.32%   70.33%           
=======================================
  Files         298      298           
  Lines       15542    15546    +4     
  Branches     3999     4000    +1     
=======================================
+ Hits        10930    10934    +4     
  Misses       4612     4612           

Files	Coverage Δ
packages/wrangler/src/ai/fetcher.ts	25.00% <20.00%> (-8.34%)	:arrow_down:

... and 6 files with indirect coverage changes