chore: Update CITATION.cff with version 1.6.7 release details

[skip ci]

Author: Paulanerus

CITATION.cff

@@ -11,11 +11,11 @@ authors:
 repository-code: 'https://github.com/Paulanerus/TextExplorer'
 url: 'https://paulee.dev/textvariantexplorer/'
 repository-artifact: >-
-  https://github.com/Paulanerus/TextExplorer/releases/tag/v1.6.6
+  https://github.com/Paulanerus/TextExplorer/releases/tag/v1.6.7
 abstract: >-
   A tool designed for the exploration, analysis, and
   comparison of textual data variants.
 license: GPL-3.0
-commit: 157183b
-version: 1.6.6
-date-released: '2025-11-11'
+commit: ee752be
+version: 1.6.7
+date-released: '2026-01-20'