updated health to use new nvim health api

[mrdandelion6]

changed all vim.health.report_* to vim.health.* to work with nvim version 11

[bkp5190]

Can this please be merged? 😀

[DmitriyBalmashnov]

In the telescope repo I saw that the merged solution worked as follows:

local health = vim.health or require "health"
local start = health.start or health.report_start
local ok = health.ok or health.report_ok
local warn = health.warn or health.report_warn
local error = health.error or health.report_error

And then locally using start() etc.
I feel like maybe this can be done here too? So that the plugin does still work for people with a lower nvim version.