fix(lsp): expert language server requires --stdio flag (#15630)

Author: 4ndv

languages.toml

@@ -47,7 +47,7 @@ elm-language-server = { command = "elm-language-server" }
 elp = { command = "elp", args = ["server"] }
 elvish = { command = "elvish", args = ["-lsp"] }
 erlang-ls = { command = "erlang_ls" }
-expert = { command = "expert" }
+expert = { command = "expert", args = ["--stdio"] }
 fennel-ls = { command = "fennel-ls" }
 fish-lsp = { command = "fish-lsp", args = ["start"] }
 forc = { command = "forc", args = ["lsp"] }