Bus timings do not load

[wilsonwid]

Describe the bug

Bus timings at available bus stops are not displayed. Furthermore, there seems to be outdated bus services as brought up by #3407.

To Reproduce

Steps to reproduce the behavior:

1. Go to nusmods.com/venues/
2. Select any venue close to a bus stop, and select said bus stop.

Expected behavior

The popout should display timings for currently available bus routes.

Screenshots

Desktop (please complete the following information):

• OS: MacOS
• Browser: Chrome

Additional context

There are also outdated bus stops and new services (service E and K come to mind) are not displayed.

[zwliew]

This issue seems to happen because the old NextBus API that we were using was taken down and replaced by nnextbus.nus.edu.sg.

Also, the new API requires auth.

[jloh02]

Found an open endpoint that's used by sets.netlify.app. There are other endpoints to get the timings for each bus stop. Not sure if we want to delve into using this though

https://urchin-app-jluem.ondigitalocean.app/api/bustimings/allstops/National%20University%20of%20Singapore