fix: Better approach to check if the system is Windows before setting PATH (#2690)

* Better approach to check if the system is Windows

Now the check for Windows doesn't depend on luv's os_uname() function, which may have a different result if neovim was built on different compilers (MSVC, MinGW, etc).

* remove un-needed parenthesis

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Co-authored-by: Sidhanth Rathod <siduck@tutanota.com>

lua/core/init.lua

@@ -57,7 +57,7 @@ for _, provider in ipairs { "node", "perl", "python3", "ruby" } do
 end
 
 -- add binaries installed by mason.nvim to path
-local is_windows = vim.loop.os_uname().sysname == "Windows_NT"
+local is_windows = vim.fn.has("win32") ~= 0
 vim.env.PATH = vim.fn.stdpath "data" .. "/mason/bin" .. (is_windows and ";" or ":") .. vim.env.PATH
 
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