🐛 BUG: `wrangler generate` sometimes fails due to cross-device renaming

### Which Cloudflare product(s) does this pertain to?

Wrangler

### What version of `Wrangler` are you using?

2

### What operating system are you using?

Windows

### Describe the Bug

Run `wrangler generate` with any template. It will fail.

The solution is to switch from `fs.renameSync` to a `copy` and `unlink` approach in `git-client.ts`