Fix issue ee_check_python(): Error in strsplit(a, "[.-]"): non-character argument

[MatthieuStigler]

should fix #392 , runs now without error:

library(rgee)
packageVersion("rgee")
#> [1] '1.1.7.9'
ee_check_python()
#> ◉  Python version
#> ✔ [Ok] /home/xxx/.cache/R/reticulate/uv/cache/archive-v0/hVk2jz0ebnIx6PZclvvcc/bin/python v3.11

^{Created on 2025-06-30 with reprex v2.1.1}