Even when the message format is incorrect, it still assigns a reviewer

[shricodev]

Describe the bug

As per the PR Pointer second bullet:

• If you need a review or an answer to a question, and don't have permissions to assign people, leave a comment like the following: "{{Question/comment}} @{{reviewer_username}} PTAL". Oppiabot will help assign that person for you.

Even when the message format is wrong it assigns the reviewer.

To Reproduce
Steps to reproduce the behavior:

1. Go to any PR thread and write a message as such "PTAL smthng smthng @mention, smthng".
2. This should assign the @mentioned guy to the PR.

Observed behavior
I have faced this error sometimes. oppia/oppia#18224 (comment)

Expected behavior
This reviewer assignment should be appropriately done with an exact match of the format else in such a conversation it will add the reviewer mistakenly.

Additional context
It seems to be on the lookout for the term PTAL anywhere in the sentence and for any instances where the same sentence contains a @mention along with some additional word, It assigns the @mention. However, this needs to be checked once manually.

[gp201]

@shricodev If you leave a comment in the following format PTAL smthng smthng @mention, smthng., it will not assign a reviewer since it does not follow the following format {{Question/comment}} @{{reviewer_username}} PTAL

[shricodev]

Hello, @gp201, would you kindly consider taking a look at the oppiabot assignment below this comment? Thanks

I have faced this error sometimes. oppia/oppia#18224