fix: atuin update on windows (#3453)

This fixes the `atuin update` command on Windows.

Windows doesn't let you overwrite a running exe, but it lets you rename
it. This PR special-cases the official `update` plugin by renaming the
running `atuin.exe` to `atuin.old` before the update, and rolling it
back if the update fails.

Note that the `atuin.old` file is left behind on success, which
shouldn't be a problem in practice: it will be overwritten on the next
call to `atuin update` (also deleted if there's no update available),
and is located in `~/.atuin/bin`, which is an isolated location specific
to Atuin.

Fixes #3451

## Checks
- [x] I am happy for maintainers to push small adjustments to this PR,
to speed up the review cycle
- [x] I have checked that there are no existing pull requests for the
same thing

0 files changed, 0 insertions, 0 deletions