fix rendering of shapes graphs

Author: Nick-Pearson

.github/workflows/book.yml

@@ -24,6 +24,7 @@ jobs:
           cd ${{ github.workspace }}/examples/financial_charts && cargo run
           cd ${{ github.workspace }}/examples/3d_charts && cargo run
           cd ${{ github.workspace }}/examples/subplots && cargo run
+          cd ${{ github.workspace }}/examples/shapes && cargo run
       - run: mdbook build docs/book
       - name: Checkout gh-pages branch
         run: |