Upkeep for readxl

[jennybc]

2020

• usethis::use_testthat(3) and upgrade to 3e, testthat 3e vignette Apparently readxl did already use testthat 3e, but not in the most current way. So I updated many tests to make greater use of snapshots.

2022

• Update errors to rlang 1.0.0 #726
  https://rlang.r-lib.org/reference/topic-error-call.html
  https://rlang.r-lib.org/reference/topic-error-chaining.html
  https://rlang.r-lib.org/reference/topic-condition-formatting.html
• Update lifecycle badges with more accessible SVGs: usethis::use_lifecycle() still no compelling authentic need to lifecycle yet in readxl

2023

Necessary:

• Double check license file uses '[package] authors' as copyright holder. Run use_mit_license()
• Update logo (https://github.com/rstudio/hex-stickers); run use_tidy_logo()
• usethis::use_tidy_coc()
• usethis::use_tidy_github_actions()

Optional:

• Review 2022 checklist to see if you completed the pkgdown updates
• Prefer pak::pak("org/pkg") over devtools::install_github("org/pkg") in README
• Consider running use_tidy_dependencies() and/or replace compat files with use_standalone() opened related issue
• use_standalone("r-lib/rlang", "types-check") instead of home grown argument checkers opened related issue
• Add alt-text to pictures, plots, etc; see https://posit.co/blog/knitr-fig-alt/ for examples