[WIP] Use raw strings (from R 4.0)

[github-actions[bot]]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if e05316663539b438046b0e0da6c46dc616e64a3a is merged into main:

• :heavy_check_mark:cache_applying: 273ms -> 275ms [-9.13%, +10.11%]
• :heavy_check_mark:cache_recording: 775ms -> 767ms [-6.44%, +4.28%]
• :heavy_check_mark:without_cache: 1.27s -> 1.28s [-2.73%, +4.66%]

Further explanation regarding interpretation and methodology can be found in the documentation.