bug#66144: 29.1; eglot-shutdown request params violate JSONRPC

[Eli Zaretskii]

> From: Javier Olaechea <pirata@gmail.com>
> Date: Sat, 7 Oct 2023 22:42:47 -0500
> 
> It seems that eglot used to send an empty object as the params but it got 
> replaced by null to appease
> gopls.
> 
> https://github.com/joaotavora/eglot/commit/4f6e152e1c5efc39a888f747ecca313a58f4375e
> 
> The fix would be replacing the call
> (jsonrpc-request server :shutdown nil :timeout (or timeout 1.5))
> with
> (jsonrpc-request server :shutdown eglot--{} :timeout (or timeout 1.5))

João, any comments?