Can no longer build doom emacs offline on another machine

### I confirm that...

- [X] I have searched the [issue tracker](https://github.com/doomemacs/doomemacs/issues), [documentation](https://docs.doomemacs.org), [FAQ](https://docs.doomemacs.org/-/faq), [Discourse](https://discourse.doomemacs.org), and [Google](https://google.com), in case this issue has already been reported/resolved.

- [X] I have read "[How to Debug Issues](https://doomemacs.org/d/how2debug)", and will use it to provide as much information about this issue as possible.

- [X] The issue can be reproduced on the **latest** available commit of Doom.

- [X] The issue can be reproduced on a stable release of Emacs, such as 27, 28, or 29. *(Unstable versions end in .50, .60, or .9x)*

### Expected behavior

Run `doom sync --rebuild` or `doom rebuild` to build emacs (after transferring .emacs.d and .doom.d from personal to work computer)

### Current behavior

When I run `doom sync --rebuild` it forces

```
> Updating recipe repos...
x The package manager threw an error
x Last 16 lines of straight's error log:
$ cd /Users/zacharyteowj/.emacs.d/.local/straight/repos/melpa/
$ git rev-parse HEAD
edbb47c3e7df4f72c21e0129e7b24bcda598a1a2
[Return code: 0]
$ cd /Users/zacharyteowj/.emacs.d/.local/straight/repos/melpa/
$ git config --get remote.origin.url
https://github.com/melpa/melpa.git
[Return code: 0]
$ cd /Users/zacharyteowj/.emacs.d/.local/straight/repos/melpa/
$ git fetch origin
fatal: unable to access 'https://github.com/melpa/melpa.git/': CONNECT tunnel failed, response 407
[Return code: 128]
```

### Steps to reproduce

1. Transfer your config from one computer to another such that this is triggered
```
! Your system has changed since last sync
Installed packages must be rebuilt. Do so now? (y or n) y
```

2. `Run sync --rebuild`

### System Information

I can't upload anything to such services as the bug is from my work computer - apologies