If you've ever ridden a bus or tram, you've probably noticed that station announcements are pre-recorded and repeat continuously. In this task, you'll create a generator function called bus_announcements to simulate an automated announcement system for bus stops.

Follow these steps:

1. Define a function bus_announcements(stops) that takes a list of bus stops as an argument.
2. Use an infinite loop (while True) to make the announcements repeat forever.
3. Inside the loop, use a for loop (for stop in stops) to go through each stop in the list.
4. Use the yield keyword to return the message "Next stop: {stop}", where {stop} is replaced by the stop's name.

When you call this generator and use next() repeatedly, it should cycle through the stops indefinitely.