Add mammoth to environment.yml to fix CI test failure

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: utkarsh0493

environment.yml

@@ -52,6 +52,7 @@ dependencies:
       - jupyter-core==5.9.1
       - jupyterlab-pygments==0.3.0
       - lxml==6.1.0
+      - mammoth==1.12.0
       - macholib==1.16.4
       - markdown==3.10.2
       - markdown-it-py==4.1.0