Update ad to next Studio webinar

Author: red-patience

_includes/layouts/webinar_plug.html

@@ -1,5 +1,5 @@
 
-   <a href="https://plotly.com/getting-started-with-studio/?utm_source=graphing_libraries&utm_medium=documentation&utm_campaign=getting-started-with-plotly-studio-1apr2026&utm_content=sidebar" target="_blank">
-     <img src="https://images.prismic.io/plotly-marketing-website-2/acGv9pGXnQHGY4G6_getting-started-with-plotly-studio-square.jpg?auto=format,compress"
+   <a href="https://plotly.com/getting-started-with-studio/?utm_source=graphing_libraries&utm_medium=documentation&utm_campaign=getting-started-with-plotly-studio-23apr2026&utm_content=sidebar" target="_blank">
+     <img src="https://images.prismic.io/plotly-marketing-website-2/ac1DPpGXnQHGZLKZ_getting-started-with-plotly-studio-april-23.jpg?auto=format,compress"
      style="width: 200px; height: 200px; position: fixed; bottom: 10px; left: 50px" alt="Sign up for the upcoming webinar: Getting Started with Plotly Studio">
    </a>