fixed lua language server name and setup

[dknueppe]

Was facing these issues:

Failed to run `config` for nvim-treesitter

/home/d/.config/nvim/init.lua:856: attempt to call field 'install' (a nil value)

# stacktrace:
  - init.lua:856 _in_ **config**
  - init.lua:257
Press ENTER or type command to continue
Error executing vim.schedule lua callback: ...l/share/nvim/lazy/mason.nvim/lua/mason-registry/init.lua:32: Cannot find package
"lua_ls".
stack traceback:
        [C]: in function 'error'
        ...l/share/nvim/lazy/mason.nvim/lua/mason-registry/init.lua:32: in function 'get_package'
        ...on-tool-installer.nvim/lua/mason-tool-installer/init.lua:269: in function 'callback'
        ...l/share/nvim/lazy/mason.nvim/lua/mason-registry/init.lua:155: in function 'refresh'
        ...on-tool-installer.nvim/lua/mason-tool-installer/init.lua:345: in function ''
        vim/_editor.lua: in function ''
        vim/_editor.lua: in function <vim/_editor.lua:0>
Press ENTER or type command to continue

Changing these 2 lines fixed it.