fix:🐛 paths not normalized for windows

[GustavEikaas]

Description

Running :lua require("git-worktree").create_worktree("nvim-btw","main","origin") on windows results in an error

The has_worktree function does not work on windows. When it tries to compare the output from git worktree list with the calculated path for the newly created worktree it does not get a match.

After adding some print statements, i see the following.

## init.lua #L229
{                                                                                                                                              
  case = "worktree_path:absolute",                                                                                                             
  data = "C:/Users/Gustav/repo/test/cli-devkit.git/abffff",                                                                                    
  path = "C:/Users/Gustav/repo/test/cli-devkit.git\\abffff"                                                                                  
} 

Reproduce

1. Use windows
2. Clone a bare repo
3. Open neovim btw
4. Run :lua require("git-worktree").create_worktree("nvim-btw","main","origin")
   You will recieve the following error message
   

Additional

My code only normalizes the path but it is worth considering using vims inbuilt api for concatenating paths
The call to :absolute() seems redundant on windows as it returns an absolute path but perhaps not on linux?

- vim.fs.normalize(Path:new(string.format("%s" .. Path.path.sep .. "%s", git_worktree_root, path)):absolute())
+ vim.fs.joinpath(git_worktree_root, path)