Fix version comparison w/ `v8_version()`

[elipousson]

I ran into some issues with the version comparison using v8_version() that should are fixed by this PR.

[ateucher]

Thanks for finding and fixing this! This is due to a new constraint added in R 4.4.0:

The numeric version creators now stop on invalid non-character version specifications.

From https://cran.r-project.org/doc/manuals/r-release/NEWS.html.

I added two more:

• https://github.com/ateucher/rmapshaper/blob/main/tests/testthat/test-clip_erase.R#L203
• https://github.com/ateucher/rmapshaper/blob/main/tests/testthat/helpers.R#L6

[elipousson]

Thanks! I couldn’t figure out exactly when it started but it drove me crazy until I caught it. Appreciate the quick review and merge.

[ateucher]

Thanks for reporting and fixing it!