How to add white border around text?

Discussed in https://github.com/has2k1/plotnine/discussions/898

^{Originally posted by aborruso December 7, 2024}
Hi,
I would like to add a thin white border to text labels

(
    ggplot(geo_df)
    + geom_map(aes(fill="costo_per_km2"), color="black", size=0.1)
    + scale_fill_cmap(cmap_name="YlOrRd")
    + geom_text(
        aes("center_lon", "center_lat", label="DEN_REGIONE"), size=8,color="black"
    )
    + labs(fill="Costo €/km²")
    + theme(
        panel_background=element_rect(fill="white"),
        panel_grid=element_blank(),
        axis_text=element_blank(),
        axis_ticks=element_blank(),
        axis_title=element_blank(),
    )
)

If I simply clone the text layers, and change the dimensions, then they turn out centered differently

    + geom_text(
        aes("center_lon", "center_lat", label="DEN_REGIONE"), size=8,color="white"
    )
    + geom_text(
        aes("center_lon", "center_lat", label="DEN_REGIONE"), size=6,color="black"
    )

This is my input file.

Thank you

Create an example in the documentation

Read the discussion at github.com/has2k1/plotnine/discussions/898 and review the linked input file to understand the requested text-label effect and the existing plotnine example. Locate the appropriate documentation example area, add a reproducible example, and verify that it demonstrates a white border around text labels without the misalignment shown in the issue.