Update info about supporting Lua 5.4 version

[bhaku]

❯ lua -v
Lua 5.4.2  Copyright (C) 1994-2020 Lua.org, PUC-Rio
❯ lua test.lua
[pass] numbers
[pass] literals
[pass] strings
[pass] unicode
[pass] arrays
[pass] objects
[pass] decode invalid
[pass] decode invalid string
[pass] decode escape
[pass] decode empty
[pass] decode collection
[pass] encode invalid
[pass] encode invalid number
[pass] encode escape