Reword Enums to Remove "Master"

[rickrizzo]

Remove the word "master" from the project. An inclusive language filter was flagging this. As this word is only used in a test I opted to remove it completely to avoid this issue for myself and others.

Master is now "graduate" and doctor is now "doctorate" to be consistent.

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary

[natecook1000]

@swift-ci Please test

[natecook1000]

Thanks, @rickrizzo!