fix: update seconds lamp every second when using system time

src/containers/TimeConverter.tsx

@@ -1,4 +1,4 @@
-import { useState } from "react";
+import { useState, useEffect } from "react";
 import { BerlinClock } from "./BerlinClock";
 import { DigitalClock } from "./DigitalClock";
 import { useCurrentTime } from "../hooks/useCurrentTime";
@@ -9,6 +9,14 @@ export function TimeConverter() {
   const [useSystemTime, setUseSystemTime] = useState(false);
   const berlinClock = dateToBerlin(currentTime);
 
+  useEffect(() => {
+    if (!useSystemTime) return;
+    const id = setInterval(() => {
+      setCurrentTime(new Date());
+    }, 1000);
+    return () => clearInterval(id);
+  }, [useSystemTime, setCurrentTime]);
+
   return (
     <div>
       <label>