[BUG] [Gitlab] How many approvals are required before an MR can be merged. Deprecated in 12.0 in favor of Approval Rules API.

**Describe the bug**
The number of approvals cannot be obtained correctly through `danger.gitlab.mr.approvals_before_merge`

**To Reproduce**
`danger.gitlab.mr.approvals_before_merge` still null

**Expected behavior**

Get the approved quantity correctly

** Your Environment**

| software | version
| ---------------- | -------
| danger.js | 10.4.0
| node | lts-alpine
| npm |
| Gitlab | 13.1.2-ee

**Additional context**
[Gitlab merge_request_approvals](https://docs.gitlab.com/ee/api/merge_request_approvals.html)

Start with danger.gitlab.mr.approvals_before_merge and the linked GitLab merge_request_approvals API documentation, noting that the title points to the Approval Rules API as its replacement. Confirm which API response should provide the approval quantity and verify that the Danger GitLab property returns the expected value instead of null.

Written by the indexing model from the issue text.