text: Title: Contribute `Gantt` to Vizro visual vocabulary 
  Body: ## Thank you for contributing to our visual-vocabulary! 🎨 
  
  Our visual-vocabulary is a dashboard, that serves a a comprehensive guide for selecting and creating various types of charts. It helps you decide when to use each chart type, and offers sample Python code using [Plotly](https://plotly.com/python/), and instructions for embedding these charts into a [Vizro](https://github.com/mckinsey/vizro) dashboard.
  
  Take a look at the dashboard here: https://huggingface.co/spaces/vizro/demo-visual-vocabulary
  The source code for the dashboard is here: https://github.com/mckinsey/vizro/tree/main/vizro-core/examples/visual-vocabulary
  
  ## Instructions
  
  0. Get familiar with the dev set-up (this should be done already as part of the initial intro sessions)
  
  1. Read through the [README](https://github.com/mckinsey/vizro/tree/main/vizro-core/examples/visual-vocabulary) of the visual vocabulary
  
  2. Follow the steps to contribute a chart. Take a look at other examples. This [commit](https://github.com/mckinsey/vizro/pull/634/commits/417efffded2285e6cfcafac5d780834e0bdcc625) might be helpful as a reference to see which changes are required to add a chart.
  
  3. Ensure the app is running without any issues via `hatch run example visual-vocabulary`
  
  4. List out the resources you've used in the [README](https://github.com/mckinsey/vizro/tree/main/vizro-core/examples/visual-vocabulary)
  
  5. Raise a PR 
  
  
  **Useful resources:**
  - Gantt: https://plotly.com/python/gantt/
  - Data chart mastery: https://www.atlassian.com/data/charts/how-to-choose-data-visualization