Github stamps not included in the trust bonus

**Overview**

Passport issues stamps for github connected account, but the trust_bonus score does not include it. Maybe it is redundant but having a stamp that has no effect seems odd.

**Steps To Reproduce**
Steps to reproduce the behavior:
1. Without github stamp, get your trust_bonus
2. Go to passport page and add github stamp
3. Go back to trust page and the score is the same

**Observed behavior**
Github passport stamp has no effect on trust_bonus.

**Expected behavior**
Github passport stamp has effect on trust_bonus.

**Additional context**

The [trust_bonus calculation](https://github.com/gitcoinco/web/blob/3e1e0f4b4d412e40443d6d5e347f3cd34ef76361/app/dashboard/tasks.py#L270) does not include github. It is reasonable to think it is included in the base 50% because user needs one to be able to login, but the stamp becomes redundant --- I was testing to see if the score change but it did not, now I know why.

Start with the trust_bonus calculation in app/dashboard/tasks.py around line 270, then trace how GitHub passport stamps are represented and included in the score. Reproduce the issue by comparing trust_bonus before and after adding the GitHub stamp; done means the calculation and its coverage reflect the expected GitHub contribution.

Written by the indexing model from the issue text.