dont foget windows

zig-ecs/build.zig

@@ -29,7 +29,7 @@ pub fn build(b: *Builder) void {
 
         // first element in the list is added as "run" so "zig build run" works
         if (i == 0) {
-            exe.setOutputDir(std.fs.path.joinPosix(b.allocator, &[_][]const u8{ b.cache_root, "bin" }) catch unreachable);
+            exe.setOutputDir(std.fs.path.join(b.allocator, &[_][]const u8{ b.cache_root, "bin" }) catch unreachable);
             const run_exe_step = b.step("run", b.fmt("run {}.zig", .{name}));
             run_exe_step.dependOn(&run_cmd.step);
         }