gatekeeper: set version

before:
 ➜ gator --version
gator version devel (unknown) (Feature State: beta), opa/v0.68.0, frameworks/v0.0.0-20241101234656-e78c8abd754a

 after:
 ➜ ./result/bin/gator --version
gator version 3.18.2 (Feature State: beta), opa/v0.68.0, frameworks/v0.0.0-20241101234656-e78c8abd754a

Author: SuperSandro2000

pkgs/by-name/ga/gatekeeper/package.nix

@@ -22,6 +22,10 @@ buildGoModule rec {
     installShellFiles
   ];
 
+  ldflags = [
+    "-X github.com/open-policy-agent/gatekeeper/v3/pkg/version.Version=${version}"
+  ];
+
   subPackages = [ "cmd/gator" ];
 
   postInstall = ''