Accept textDocument argument in textDocument/didSave handler.

According to the spec, the didSave handler takes the same textDocument
property as the other textDocument handlers, rather than having uri as
a top-level field.

https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textSynchronization-side

src/fennel-ls/handlers.fnl

@@ -273,7 +273,7 @@ Every time the client sends a message, it gets handled by a function in the corr
   (send (message.diagnostics file))
   (set file.open? true))
 
-(λ notifications.textDocument/didSave [server _send {: uri}]
+(λ notifications.textDocument/didSave [server _send {:textDocument {: uri}}]
   (when (utils.endswith uri "flsproject.fnl")
     (config.reload server))