chore: update @kt3k/signal

Author: kt3k

deno.json

@@ -19,7 +19,7 @@
   },
   "imports": {
     "@b-fuze/deno-dom": "jsr:@b-fuze/deno-dom@^0.1.47",
-    "@kt3k/signal": "jsr:@kt3k/signal@^0.3.0",
+    "@kt3k/signal": "jsr:@kt3k/signal@^0.4.0",
     "@std/assert": "jsr:@std/assert@^1.0.0",
     "@std/async": "jsr:@std/async@^1.0.0",
     "@std/testing": "jsr:@std/testing@^1.0.0"