[Reviews] Offer's authorAvgRating is not calculating for students

**Description:** Author's average raing in offer model is not calculating for students (look into hooks in Review model)

**Reproducible:** always.

**Preconditions:**
The user is logged in.

**Steps to reproduce:**
1. Create a review for a student

**Actual result:**
authorAvgRating field doesn't change

**Expected result:**
authorAvgRating must be updated