Don't Disable UTF-8 Module on Lua < 5.3

[MikuAuahDark]

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Annotations, Libraries

Expected Behaviour

local utf8 = require("utf8") gives UTF-8 function definitions regardless of Lua version.

Actual Behaviour

local utf8 = require("utf8") only gives UTF-8 function definitions if Lua runtime version is 5.3 or later.

Reproduction steps

Reproducible with one line of code.

local utf8 = require("utf8")

On Lua runtime < 5.3, utf8 is unknown.

Additional Notes

Some Lua < 5.3 environments (e.g. love) provides Lua 5.3 utf8 module but this must be loaded separately using require.

It's reasonable to have utf8 in global namespace when user runtime is set to Lua 5.3 or later, but don't put the utf8 module in Lua 5.3 check, a.k.a. allow it to be loaded manually using require on earlier Lua version.

Log File

N/A, easily reproducible.

[sumneko]

Should be resolved by setting runtime.builtin, but it dose not work now.