Update length type from enum to string in summarization ability

[ocean90]

What?

Corrects the type value for the summarization ability because enum is no type.

Why?

Ensures part of #346 is fixed.

How?

Replaces 'enum' with 'string'.

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[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.85%. Comparing base (32c5e2d) to head (6f193ba).
⚠️ Report is 13 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop     #347   +/-   ##
==========================================
  Coverage      57.85%   57.85%           
  Complexity       615      615           
==========================================
  Files             46       46           
  Lines           3165     3165           
==========================================
  Hits            1831     1831           
  Misses          1334     1334           

Flag	Coverage Δ
unit	57.85% <100.00%> (ø)

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