Discover: Subscribe button is not getting updated in category view

### Description

The subscribe button does not turn green after subscribing to a podcast, and it doesn't change back when we unsubscribe from a podcast

### Step-by-step reproduction instructions

1. Go to Discover tab
2. Select a category
3. Subscribe to a podcast from the podcast filtered list
4. ❌ See the subscribe button does not update to green
5. Open this podcast you subscribed and unsubscribe it
6. Go back to discover
7. ❌ See the subscribe button does not reflect that you unsubscribed the podcast

### Screenshots or screen recording

https://github.com/Automattic/pocket-casts-ios/assets/42220351/0e08de5c-570f-4315-a2f4-d8c839dc6c5e

### Did you search for existing bug reports?

- [X] I have searched for existing bug reports.

### Device, Operating system, and Pocket Casts app version

Pocket Casts `7.62.0.3`