publisher-github fails on Windows if files already exist in target release

### Pre-flight checklist

- [X] I have read the [contribution documentation](https://github.com/electron-userland/electron-forge/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [code of conduct](https://github.com/electron/electron/blob/main/CODE_OF_CONDUCT.md) that this project uses.
- [X] I have searched the issue tracker for a bug that matches the one I want to file, without success.

### Electron Forge version

6.0.0-beta.61

### Electron version

v15.3.0

### Operating system

windows-latest (GitHub Actions)

### Last known working Electron Forge version

_No response_

### Expected behavior

When publishing Mac files, if the files already exist in the release, they are either ignored or silently overwritten (it's not clear which). I would expect the same to happen when publishing Windows files.

### Actual behavior

If the release doesn't exist or doesn't have Windows files in it already, the publisher works fine. If it _does_ exist and have Windows files, I see the incredibly verbose error log shown in Additional Info. Even though it looks like an internal GitHub error, I consistently see this issue only when attempting to republish existing releases (for example to test a new release workflow).

### Steps to reproduce

1. Create a tag in GitHub matching the package.json version
2. Release to that version with `electron-forge publish`
3. Release to that version again with `electron-forge publish`

### Additional information

Log from failing publish:
```
✖ Uploading Artifacts 2/1 to v0.21.0

An unhandled error has occurred inside Forge:

Unicorn! · GitHub

body {
background-color: #f1f1f1;
margin: 0;
font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
}

.container { margin: 50px auto 40px auto; width: 600px; text-align: center; }

a { color: #4183c4; text-decoration: none; }
a:hover { text-decoration: underline; }

h1 { letter-spacing: -1px; line-height: 60px; font-size: 60px; font-weight: 100; margin: 0px; text-shadow: 0 1px 0 #fff; }
p { color: rgba(0, 0, 0, 0.5); margin: 10px 0 10px; font-size: 18px; font-weight: 200; line-height: 1.6em;}

ul { list-style: none; margin: 25px 0; padding: 0; }
li { display: table-cell; font-weight: bold; width: 1%; }

.logo { display: inline-block; margin-top: 35px; }
.logo-img-2x { display: none; }
@media
only screen and (-webkit-min-device-pixel-ratio: 2),
only screen and ( min--moz-device-pixel-ratio: 2),
only screen and ( -o-min-device-pixel-ratio: 2/1),
only screen and ( min-device-pixel-ratio: 2),
only screen and ( min-resolution: 192dpi),
only screen and ( min-resolution: 2dppx) {
.logo-img-1x { display: none; }
.logo-img-2x { display: inline-block; }
}

#suggestions {
margin-top: 35px;
color: #ccc;
}
#suggestions a {
color: #666666;
font-weight: 200;
font-size: 14px;
margin: 0 10px;
}