After posit-dev/py-shiny#999 was merged into py-shiny, plotnine no longer needed a custom build for shinylive.

However, we are not able right now to use the current release version of plotnine (0.12.4), because it requires matplotlib>=3.6.0, and the version of Pyodide we are currently using includes matplotlib 3.5.2

After updating Pyodide, we will be able to switch to the newer version of plotnine.