fix(ci): add python-multipart dep for Modal deploy

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: beveradb

.github/workflows/deploy-to-modal.yml

@@ -37,7 +37,7 @@ jobs:
         run: |
           pip install modal
           # Install dependencies needed to parse deploy_modal.py
-          pip install fastapi filetype
+          pip install fastapi filetype python-multipart
 
       - name: Deploy to Modal
         env: