don't force dark background on users

we should not force this line on users:
https://github.com/LunarVim/lunar.nvim/blob/29eedf78c430ad9acebdcba814d77619edbe2bac/lua/lunar/init.lua#L7

see https://github.com/LunarVim/LunarVim/issues/3441 for more info

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also, we probably should not force this either:
https://github.com/LunarVim/lunar.nvim/blob/29eedf78c430ad9acebdcba814d77619edbe2bac/lua/lunar/init.lua#L12