refactor: simplify startSystemUpdateTicker using time.Tick (#347)

According to the Go 1.23 documentation, the garbage collector can now recover unreferenced tickers created with time.Tick, making time.NewTicker method unnecessary in most cases.

Reference:

* time.Tick: https://pkg.go.dev/time#Tick

beszel/internal/hub/hub.go

@@ -227,8 +227,8 @@ func (h *Hub) Run() {
 }
 
 func (h *Hub) startSystemUpdateTicker() {
-	ticker := time.NewTicker(15 * time.Second)
-	for range ticker.C {
+	c := time.Tick(15 * time.Second)
+	for range c {
 		h.updateSystems()
 	}
 }