fix: #657 Remove duplicate set of namespace_id

Prevent NoSuchElementException from PagerSpliterator class

feat: add generate changelog api support

Add more field to NoteEvent.ObjectAttributes

build: temporary skip tests on github action

fix: #676 Added missing values in PipelineStatus enum

Pass "masked" parameter to create/updateVariable

feat: Add various fields to project model

- readme_url
- can_create_merge_request_in
- import_status
- ci_default_git_depth
- remove_source_branch_after_merge
- auto_devops_enabled
- auto_devops_deploy_strategy
- auto_devops_enabled
- statistics.packages_size
- shared_with_groups.group_full_path

fix #613 #632 #667

test: Add tests for EmailOnPushService

Add support for email on push integration.

fix: #612 Update path for delete commit discussion note

Fixed ClassCastException when getting label name

feat: add support for GitLab merge request reviewers

Update AccessLevel.java

On gitlab.com I got 
```
org.gitlab4j.api.models.AccessLevel forValue
WARNING: [5] is not a valid GitLab access level.
```
so I've added that enum here

Added option to preserve underscores in the JacksonJsonEnumHelper to fix TargetType.MERGE_REQUEST value. (#615)