[BUG] Don't disable image logos when running inside tmux

[heather7283]

This commit https://github.com/fastfetch-cli/fastfetch/commit/71cba2451a13fdb56bbbdca943a3fb8fd194d901 disables image logos if fastfetch is running inside a tmux session, however it seems unnecessary, for me sixel logos work perfectly fine inside tmux (see screenshot). It is possible to work around this by just unsetting TMUX envvar, but is it really necessary? I can't say anything about GNU screen and zellij since I don't use them, but I think that TMUX check should be removed