Don't require exact string for response

Right now a user must react with their emoji and their emoji only.

eg.

We send: ` respond with 🦄`
They **have** to send `🦄`

Instead, we should let them send **any** text that contains `🦄`.

Look for the code that processes user responses to reminders, likely in a service file handling message parsing. The change is to check if the response string contains the required emoji rather than requiring an exact match. Test by sending a reminder and verifying a response containing the emoji is accepted.

Written by the indexing model from the issue text.