fix: error loading module '...' from file libfff_nvim

[Irdis]

It addresses issue #164

[SandyJackson]

Can confirm same error on Mac OS (ARM) is fixed by this change.

In my case the file ext. is .dylib as opposed to .dll (as you would expect).

FWIW libfff_nvim.dylib exists in target/. But Irdis your explanation in the issue makes sense to my (amateur) eye.

The fix also works if you just go back to donwnload.lua and change the get_binary_path function (line 19-23).

local function get_binary_path(plugin_dir)
  local binary_dir = get_binary_dir(plugin_dir)
  local extension = system.get_lib_extension()
  return binary_dir .. '/lib?.' .. extension
end

I am no expert and cannot comment on if this is the best/an appropriate solution but the above change is functionally the same and simpler than the current PR. (great work finding and fixing though @Irdis you've saved me hours of work that probably still wouldn't have yielded a result!

EDIT: I also use blink.cmp