rename sched to scheduler

src/kernel/tests.zig

@@ -14,7 +14,7 @@ const danos = @import("danos");
 const arch = @import("arch");
 const pmm = @import("pmm.zig");
 const heap = @import("heap.zig");
-const sched = @import("sched.zig");
+const sched = @import("scheduler.zig");
 const ipc = @import("ipc.zig");
 
 /// Formatted write straight to serial, independent of the framebuffer console.