Added MAINTAIN and TRIAGE to GHOrganization.Permission enum

[Javaru]

Description

The GHOrganization.Permission enum is missing the MAINTAIN and TRIAGE permissions. Currently the enum only has ADMIN, PUSH, and PULL. The five possible permissions are listed in the GitHub documentation for the permissions parameter for organization teams and collaborators.

Before submitting a PR:

We love getting PRs, but we hate asking people for the same basic changes every time.

• Push your changes to a branch other than master. Create your PR from that branch.
• Add JavaDocs and other comments
• Write tests that run and pass in CI. See CONTRIBUTING.md for details on how to capture snapshot data.
• Run mvn clean compile locally. This may reformat your code, commit those changes.
• Run mvn -D enable-ci clean install site locally. If this command doesn't succeed, your change will not pass CI.

When creating a PR:

• Fill in the "Description" above.
• Enable "Allow edits from maintainers".

[bitwiseman]

I would generally expect tests but I'm okay in this case with taking the new values based on manual review. Thanks!