:PaqUpdate errors when branch points at a tag

[jose-elias-alvarez]

Describe the bug
Running :PaqUpdate when a plugin's branch points at a tag shows a message indicating that updating the plugin failed.

To Reproduce

1. Install paq-nvim according to the README, then add the following plugin specification using the syntax suggested in [Feature Request] Support for tagging certain versions #144:

require("paq")({
    { "saghen/blink.cmp", branch = "v0.8.2" },
})

2. Run :PaqInstall, which succeeds
3. Restart Neovim and run :PaqUpdate
4. Observe that an error message is displayed:

Paq: [0/1] Failed to update blink.cmp

Expected behavior
No error message is shown.

Environment:

• nvim --version: 0.10.3
• git --version: 2.47.1
• OS: macOS Sequoia 15.2

Additional info

After the above operation, paq.log contains the following:

You are not currently on a branch.
Please specify which branch you want to merge with.
See git-pull(1) for details.

    git pull <remote> <branch>

It seems that git pull --recurse-submodules --update-shallow is failing because the repo is in a detached state, since the tag isn't backed by a branch. I'm not an expert, but I can imagine two solutions:

1. Check if a tag is checked out and skip updating (i.e. consider the tag to be frozen, as if it pointed at a specific commit)
2. Add --tags --force to the pull command (this seems to be what mini.deps does here, and it successfully handles this case)