Update in `RELEASE` mode script

### Is your feature request related to a problem?

If you run `./install.sh` in the directory that you installed in `RELEASE` mode, you cannot update it.

### The solution I'd like

I think we can use the .git folder to clone.
https://git-scm.com/book/en/v2/Git-on-the-Server-Getting-Git-on-a-Server

Maybe some setup work is needed ([bare = false](https://stackoverflow.com/questions/11856690/setting-the-work-tree-of-each-bare-repo), Synchronize with files using branch and tag information).

### Screenshots or video

_No response_

### Alternatives I've considered

_No response_

### Additional context

#532

Start with ./install.sh and trace the RELEASE-mode path that prevents updates in an existing installation. Read the linked context in issue #532 and review the repository's .git and work-tree requirements; done means running the installer from a RELEASE-mode installation successfully updates its files.

Written by the indexing model from the issue text.