bug: `client.requests` is deprecated

[sghng]

Describe the bug

- ⚠️ WARNING client.request is deprecated. Feature will be removed in Nvim 0.13
  - ADVICE:
    - use client:request instead.
    - stack traceback:
        /Users/sghuang/.local/share/nvim/lazy/lspsaga.nvim/lua/lspsaga/symbol/head.lua:89
        /Users/sghuang/.local/share/nvim/lazy/lspsaga.nvim/lua/lspsaga/symbol/head.lua:177
        [C]:-1
        /opt/homebrew/Cellar/neovim/HEAD-f1a8bb4/share/nvim/runtime/lua/vim/lsp/client.lua:1091
        /opt/homebrew/Cellar/neovim/HEAD-f1a8bb4/share/nvim/runtime/lua/vim/lsp/client.lua:593
        vim/_editor.lua:0

Similar to #1543

Steps to reproduce

:checkhealth deprecated

Expected behavior

NA

Neovim version (nvim -v)

NVIM v0.12.0-dev-1224+gf1a8bb45ca-Homebrew

lspsaga commit

8efe00d

Terminal name/version

Ghostty

[utakotoba]

PR #1546 exists and fixes this issue, but the main upstream hasn't merged it yet. Perhaps you could checkout and apply the patch from that PR to temporarily suppress the warning.