Adding logo to a plot using `layout` doesn't work with local images.

It appears that if you add a logo to a plotly figure using the layout function, it only works when using a remotely hosted image. Using the example on the logo tutorial, the logo is added to the plot if you point to a remote url, but not if you point to a local image:

library(plotly)

# photo used in Plotly logo example page
url <- "https://images.plot.ly/language-icons/api-home/python-logo.png"
download.file(url, "./python-logo.png")

fig <- plot_ly(x = c(1, 2, 3), y = c(1, 2, 3))
fig <- fig %>% add_lines() 
this_works <- fig %>%
  layout(
    images = list(
      list(source = url,
           xref = "paper",
           yref = "paper",
           x= 0,
           y= 1,
           sizex = 0.2,
           sizey = 0.2,
           opacity = 0.8
      )
    )
  )

this_doesnt <- fig %>%
  layout(
    images = list(
      list(source = "./python-logo.png",
           xref = "paper",
           yref = "paper",
           x= 0,
           y= 1,
           sizex = 0.2,
           sizey = 0.2,
           opacity = 0.8
      )
    )
  )

^{Created on 2023-05-23 with reprex v2.0.2}

从 issue 中显示的 layout(images = ...) 入口点开始，比较其远程 URL 和本地图像源的处理方式。使用下载的 python-logo.png 重现该示例；当本地图像像远程图像一样出现在 plot 中时，即表示完成。