plugins/lsp: fix incorrect inlay_hint usage

The previous implementation used an outdated function signature, which
no longer works. Switched to the correct usage as-per the docs.

plugins/lsp/default.nix

@@ -212,7 +212,7 @@ in
       plugins.lsp.onAttach = mkIf cfg.inlayHints ''
         -- LSP Inlay Hints {{{
         if client.server_capabilities.inlayHintProvider and vim.lsp.inlay_hint then
-          vim.lsp.inlay_hint.enable(bufnr, true)
+          vim.lsp.inlay_hint.enable(true, { bufnr = bufnr })
         end
         -- }}}
       '';