Upkeep for rmapshaper (2023)

[ateucher]

• usethis::use_tidy_description()
• Align the names of R/ files and test/ files for workflow happiness. The docs for usethis::use_r() include a helpful script. usethis::rename_files() may be be useful.
• usethis::use_code_of_conduct()
• Add alt-text to pictures, plots, etc; see https://posit.co/blog/knitr-fig-alt/ for examples

Set up or update GitHub Actions.
Updating workflows to the latest version will often fix troublesome actions:

• usethis::use_github_action('check-standard')
• usethis::use_github_action('pkgdown')
• usethis::use_github_action('test-coverage')
• Update bundled mapshaper node library.

^{Created on 2023-06-07 with usethis::use_upkeep_issue(), using usethis v2.2.0}