gitaly: buildFlags -> tags

pkgs/applications/version-management/gitlab/gitaly/default.nix

@@ -37,7 +37,7 @@ in buildGoModule rec {
     inherit rubyEnv;
   };
 
-  buildFlags = [ "-tags=static,system_libgit2" ];
+  tags = [ "static,system_libgit2" ];
   nativeBuildInputs = [ pkg-config ];
   buildInputs = [ rubyEnv.wrappedRuby libgit2 openssl zlib pcre http-parser ];
   doCheck = false;