Remove tmux references

These aren't needed as I'm now using Zellij.

lib/default.nix

@@ -77,7 +77,6 @@ rec {
       vim-terraform
       vim-textobj-user
       vim-textobj-xmlattr
-      vim-tmux-navigator
       vim-unimpaired
       vim-zoom
 
@@ -122,7 +121,6 @@ rec {
           scss
           sql
           terraform
-          tmux
           twig
           typescript
           vim

lua/opdavies/keymaps.lua

@@ -22,8 +22,6 @@ set("v", "<left>", "<nop>")
 set("v", "<right>", "<nop>")
 set("v", "<up>", "<nop>")
 
-set("n", "<C-f>", ":silent !tmux neww t<CR>", { noremap = true, silent = true })
-
 -- Easily switch back to visual mode.
 set("i", "jk", "<Esc>")