Fix GET sortby, tests

[jonhealy1]

Related Issue(s):

• 25

Description: Fixes GET sortby functionality. Adds tests.

PR Checklist:

• [x] Code is formatted and linted (run pre-commit run --all-files)
• [x] Tests pass (run make test)
• [x] Documentation has been updated to reflect changes, if applicable
• [x] Changes are added to the changelog