Apply the wiki's fix for screen tearing

- See <https://nixos.wiki/wiki/Nvidia>'s section on how to "Fix screen tearing"
diff --git a/modules/nvidia.nix b/modules/nvidia.nix
index f7aa1bd..8ae9a7f 100644
--- a/modules/nvidia.nix
+++ b/modules/nvidia.nix
@@ -10,7 +10,14 @@
 in
 {
   config = {
-    services.xserver.videoDrivers = [ "nvidia" ];
+    services.xserver = {
+      videoDrivers = [ "nvidia" ];
+      screenSection = ''
+        Option         "metamodes" "nvidia-auto-select +0+0 {ForceFullCompositionPipeline=On}"
+        Option         "AllowIndirectGLXProtocol" "off"
+        Option         "TripleBuffer" "on"
+      '';
+    };
     hardware = {
       opengl.enable = true;
       nvidia = {