ANW-1483: correct maintenance states strings in EAC-CPF export

[avatar382]

Description

Correcting export strings so they conform to EAC/CPF

Related JIRA Ticket or GitHub Issue

https://archivesspace.atlassian.net/jira/software/c/projects/ANW/issues/ANW-1483

How Has This Been Tested?

manual and unit testing

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have read the CONTRIBUTING document.
• I have authority to submit this code.
• I have added tests to cover my changes.
• All new and existing tests passed.

[cdibella]

@avatar382 thanks for doing this. Looking at the file changes, I think this line at the end of the JIRA may have slipped your notice:

"Also, an additional status of deletedMerged is needed."