ci: add GitHub Actions user to fix mike deploy

.github/workflows/build_docs.yml

@@ -17,5 +17,12 @@ jobs:
         with:
           key: ${{ github.ref }}
           path: .cache
+
       - run: pip install mkdocs-material mike
+
+      - name: Configure Git user
+        run: |
+          git config --local user.email "github-actions[bot]@users.noreply.github.com"
+          git config --local user.name "github-actions[bot]"
+
       - run: mike deploy --push dev