Add missing dependency (#25)

Author: AdrienVannson

.github/workflows/documentation.yml

@@ -16,13 +16,13 @@ jobs:
           git config user.email 41898282+github-actions[bot]@users.noreply.github.com
       - uses: actions/setup-python@v5
         with:
-          python-version: 3.x
+          python-version: 3.12
       - run: echo "cache_id=$(date --utc '+%V')" >> $GITHUB_ENV 
       - uses: actions/cache@v4
         with:
           key: mkdocs-material-${{ env.cache_id }}
           path: .cache
           restore-keys: |
             mkdocs-material-
-      - run: pip install mkdocs-material 
+      - run: pip install mkdocs-material mkdocstrings
       - run: mkdocs gh-deploy --force