chore(third_party/geesefs): move to expression in nixpkgs

This now exists in nixpkgs, and a more recent version of it.

Change-Id: I51fe038ba9459587952028f77e97b48212d13e74
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11762
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

users/tazjin/nixos/modules/geesefs.nix

@@ -28,7 +28,7 @@
 
       mkdir -p $STATE_DIRECTORY/tazjins-files $STATE_DIRECTORY/cache
 
-      ${depot.third_party.geesefs}/bin/geesefs \
+      ${pkgs.geesefs}/bin/geesefs \
         -f -o allow_other \
         --cache $STATE_DIRECTORY/cache \
         --shared-config $CREDENTIALS_DIRECTORY/geesefs-tazjins-files \