Fix typst install: use setup-typst action

The curl-based install returned 404. Use the official
typst-community/setup-typst@v4 GitHub Action instead.

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

Author: pthom

.github/workflows/deploy_docs.yml

@@ -36,11 +36,10 @@ jobs:
         with:
           python-version: '3.x'
 
+      - uses: typst-community/setup-typst@v4
+
       - name: Install dependencies
-        run: |
-          pip install -r docs_src/requirements.txt
-          curl -fsSL https://typst.community/typst-install/install.sh | bash
-          echo "$HOME/.local/bin" >> $GITHUB_PATH
+        run: pip install -r docs_src/requirements.txt
 
       - name: Build docs
         env: